People who talk about politics and religion at work tend to get hated at best and fired at worst.

People who talk about politics and religion on social media risk getting lectures from relatives and losing friends.

So yeah, people do not talk about politics and religion in America a lot of the time.

Honestly, the only reason my mother-in-law and I have maintained a really good relationship over the decades is because we just don't talk about religion or politics. My wife and I are pretty much on the opposite side of the map from her on both. So we just don't talk about it rather than become enemies. Maybe that's not the right way to go about things, but it's saved a lot of stress where we don't need it.

In my experience, yes. Mainly because for as long as I’ve been alive, if you have a dissenting opinion people tend to get very heated.

Obviously we still have political protesters and things like that but nowadays things are so divided politically that it is typically a topic that you would avoid in everyday conversation. If you were to bring up anything political with your coworker at a get together after hours for example and you find that you are on opposite ends of the political spectrum it could make it very difficult to work together at best and potentially endanger you at worst.

that and religion are no no's.

i googled it and found lots of treatises on the subject

American politeness? No

It's more of a thing so you aren't constantly fighting with your family.