I mean, if you really want to make the government subsidize an ID verification scheme or mandate that certain real-world locations provide age verification as a social service for everyone, that's fine.
It's orthogonal to the discussion, though, which is about whether we should do it or not, because the costs here aren't significant and don't change the terms of the debate.
I'm personally in favor of just banning children off the Internet, but I don't agree it's orthogonal to the discussion. What I replied to was the implication that someone should pay a recurring cost to prove they're an adult for the same reason that they pay to own a computer or to connect to the Internet. Don't disown the dumb thing you said.