Some channels won't air swearing, so they can reach better deals with providers. That's not a law.

> But also that you can't say "shit" on American TV.

Yes, you can. South Park is on American TV, after all.

It is most definitely not on the air in the US. It is only available through “private” cable and satellite networks. We still have, and enforce censorship laws on public over-the-air broadcasts.

Here’s the overview of the rules, and you can in fact say shit on the air:

https://www.fcc.gov/consumers/guides/obscene-indecent-and-pr...