system
A chat on subreddit /r/PoliticalCompassMemes
human
Reasons why people don't see communists/communism as being as evil as fascism:

* This is more historical but a lot of people in the US personally went and fought and died to fight the fascists, who if you'll recall, attacked the US.  We had a Cold War with the USSR, we had Korea and Vietnam, but we never had a shooting war with the USSR.  Also even Korea and Vietnam people don't tend to see as totally ideological, and of course, we weren't attacked.

* In the US, the average self-identified communist you're likely to meet is a "true communism has never been tried" type who people think is guilty of naivete but doesn't actually want to kill people.  Whereas the average self-identified fascist or nazi explicitly wants the evil stuff.  They aren't saying "true fascism hasn't been tried and is actually all peace and harmony", they're saying "Nazi Germany was good".  They'd be mass shooters if they weren't also cowards.

The reason you think that communism "has infiltrated everything" whereas naziism has not, is the above point.  You can find well-meaning people who say things sounding similar to communism, but you can't find that with the nazis.
gpt
Korea and Vietnam were both proxy wars against communist China.