> Adults can be prosecuted for helping minors circumvent the checks.

If you skip the need for privacy protection and just retain a copy of the photo ID used to verify the account? Then sure.

But if age is validated in a way that preserves privacy? Then there's no evidence linking the adult to the crime.

"No evidence" doesn't make it not a crime. Most people wouldn't do crime even if no one found out.

And once that adult committed a crime anyone involved can report it, including that minor friend. It's blackmail material. Better not fall out!