Who is this "they" you speak of?
We have age verification for all kinds of things that can harm minors. Most of them have adequate penalties for breach such that operators of said harms ensure they comply (checks for ID when selling alcohol, entry to over-18s pubs/clubs, etc.)
There's nothing sinister going on here, just attempts to prevent social/mental harm to minors.
> There's nothing sinister going on here
There absolutely is you're just not aware of it.
This whole thing is meta financially backing right wing conservative groups that want age verification because meta wants to avoid liability for the harms their platforms cause.
In addition, this is the beginning of the end of any sort of anonymity on the internet, which has disastrous consequences for politically minded individuals, minority populations, or targets of stalking. This is a privacy nightmare bring pushed through in the guise of "muh children".