You would be correct there are no "banned books" in America.

When people say "banned book" they mean that a certain level of government such as a school board or municipality has "banned" them from being in a public (often school) library.

But the headline "In [state I disagree with] they are banning books that have [ideas I agree with]" makes a lot more headlines and clicks.

Then people run with the phrase "banned books" to make things sound worse than they are.