How does a field carrying age sniffing? It's open source, you personally run whatever you want.

But not all places are like that, Linux is run in places where abusing this law is mandated. The alternative is that that place can't run Linux - so by denying such a feature you actually deny the usage of Linux, limiting "user-freedom".

You are by no ways hurt if you choose to either ignore the law or live in a place where such laws won't be passed.

(With that said, I'm absolutely against age verification - but that in and of itself won't change the law)