After World War II, Germany went through a long process of Denazification. Schools taught anti-Nazi curriculum and by the 60s, laws were enacted making it illegal to even jokingly goosestep and nonsense like that.
So why is it that countries like America and Britain seem to find it okay to still associate Germany with being the Third Reich?
Looking into American popular culture, works taking place in Germany made in the United States being set in or around World War II such as Hogan's Heroes, about every World War II FPS out there, the failed sitcom Heil Honey I'm Home! and every war movie ever made seem to be the only instance Germany is ever seen in pop culture in America. Never have we had tales of modern Germany; a whole grand drama could be made about East and West Germany.
But by nature, World War II is by far where the German people are most exposed to modern culture. Strangely enough, there is no All Italians Are Fascists trope, even though Mussolini's granddaughter is a significant figure in current Italian politics (and hers isn't the only ultra-nationalist party), nor is there an All Spaniards Are Francoists trope, even though that regime lasted into the 1970s and was never really deposed. There isn't even an All Japanese Are Militarists trope, and they have an even longer history of militarism than the Germans (not in the West, anyway; attitudes towards the Japanese by the Chinese and Koreans remain decidedly negative).
This may have to do with the Nazis being so much more infamous than any other Fascists — mainly because of all the countries they invaded (Spain was neutral in WWII, and Italy tried a bunch of invasions, but wasn't very good at it) and, of course, being responsible for The Holocaust — Israel, Poland, Romania, Russia, and other such countries have very good reason to not let Germany live down its actions in WWII. This may also have to do with the fact that Germany was the main threat in WWII, despite not killing a whole lot more people than Japan. Or perhaps because, unlike other Axis nations, where only the leadership were tried for war crimes following the war, the official policy of the Allies was to assign collective guilt
to the German people for Nazi atrocities. This has, incidentally, worked very well, and the German educational system is seen as an excellent example of how to get a country to recognize and come to terms with the nastier parts of its history (it is compulsory for all Germans to learn about WWII and the Holocaust), something Japan and Italy have been pretty bad at. Accordingly, this Trope is generally a Berserk Button for modern Germans.
Some (particularly American military theorists, Eastern European leaders, and occasionally the French) say it worked too well, as it's given Germany a war-phobia that has occasionally threatened NATO missions (not to mention their own nation's freedom of speech) and Western unity in general. The German "No" vote — as opposed to the expected abstention — on the United Nations resolution authorizing intervention in Libya was seen as particularly damaging; Nicolas Sarkozy in particular essentially told Merkel "what the hell were you thinking?" in response.note
There is also the fact that the 30s and 40s were the first decades of mass-media. An era of sound newsreels, widespread radio broadcasts and information, and the decades of sound cinema. This corresponded with the 12 years of the mercifully-cut-short 1000 year reich. Related to this is that the Nazis were highly media-savvy and they quickly embraced the emerging mass media spectacles. The general public of the Western world exposed to newsreels were highly familiar with images from Nazi Book Burnings, rallies, the Berlin Olympics. This also worked within Germany itself, portraying the Nazi party as being so powerful virtually all Germans supported it, to demoralize the opposition into silence and inaction. Even before World War II, Hitler and the Nazis were highly visible figures. As such, the Nazis both before and after the war disseminated the most widely seen visual images of German culture for the movie-going audience. More refined members of the public knew of German philosophy and high culture, they may also have been familiar with the Weimar avant-garde of the 20s (many of whose key representatives became exiles who worked in America), but these were far less widely seen and experienced than the images of Nazi Germany. World War II merely magnified that and set in stone. The rise of sound cinema also played a key role in the development of English and especially American English as the global language; that, coupled with the hegemony of Hollywood, further aided in solidifying this trope in the common perception of what Germany was and is. It didn't help that the Nazis were, well, Nazis and weren't keen on the whole "freedom of speech" thing. If a German spoke out against Hitler or the party, he or she could get in serious trouble. You couldn't walk into Hitler's office and pound on his desk and say "cancel the Holocaust" right now. note . Silencing the opposition this way is a classic trick in totalitarian states to project the image (both abroad and internally) that the leader/party is uncontested in power and everyone is on their side.
It's important to know Hitler wasn't actually voted in power, at least not in the way most democracies work. He became chancellor when the (arguably senile) President Hindeburg appointed him to the job in 1932. The Nazi party never achieved more than 44% of the seats in the Reichstag even after insane amounts of voter intimidation and other undemocratic tricks. An alarming number to be sure, but not enough to have total power, and certainly not enough to amend the Weimar constitution. What sealed the deal was the Nazis making deals with other parties who saw the Nazis as the lesser evil against the communists. The Reichstag fire in 1933 was blamed on the communists and the Reichstag (the assembly, not the building) voted to ban the communist party, removing opposition to the Nazis. While it was definitely a case of arson, it's still not clear if the Nazis pulled a False Flag Operation and blamed it on the communists, or if it was caused by another group and the Nazis used the opportunity note . In 1934, shortly before Hindenburg died, the Nazis and their coalition partners made sure that the office of President would be merged with the Chancellorship, making Hitler Fuhrer and making it impossible to remove it from office short of his death. That was basically it for democracy, and it effectively sealed the fate of Germany until 1945. It needs to be kept in mind, again, that we have the benefit of hindsight, but at the time Hitler was careful to hide his megalomania and project a good image. His rhetoric, although disgusting to us today, would not necessarily have been that far-fetched to audiences of the time, even in other western countries like the United States, the United Kingdom, France and Canada, who had fascist and semi-fascist groups of their own. There was not anything special about the German people that made them more prone to falling to fascism, and under different circumstances the same could have happened in countries that would become the Allies in WW2. In fact Germany under the Weimar Republic was surprisingly diverse politically.
It should also be noted, that there isn't a binary between "not a Nazi" and "would enthusiastically murder innocent people". The Nazi party absolutely included "moderates" who, while having genuine anti-Semitic sentiments and other bigoted views, were genuinely repulsed by the worst atrocities of the Nazis. That is not to excuse their evil and their participation in a criminal regime, but human morality is complex and rarely Black and White. For instance, before and during The American Civil War there were many people who genuinely believed Black slaves deserved to be free (and for altruistic reasons, not economical or political ones), but most of them still held opinions that we would consider extremely racist today, or at least very condescending.
Much like how the America Saves the Day trope is still played straight at times in current media, the existence of such an easy and irredeemable villain in the normally Grey or Black business that is war means that this trope got and still gets a lot of mileage.
