Lots of US states, European countries, and Australia have introduced “age verification” regulations. They present it as the classic “save the children” talking point, but it’s really just a precursor to attribution of speech, particularly attributing your words to your real identity.
What do you mean “no evidence”? That’s not the issue at hand here. The issue is that age verification (as implemented now) opens up these possibilities for future law makers. The reason people are concerned is because of a slippery slope.