Earlier quoted context omitted.
That's a parent issue, the same as if their kid has a secret stash of cocaine or enjoys dancing in traffic. No technical measure can fix stupid.
That's not parents issue. That's why we go after people who sell or give drugs to kids. Is a serious offense, we don't wave our hands and say its parents problem and not drugging kids is a popular policy unlike drug enforcement for adults.
The fundamental point is that the Internet is not a daycare. All of these attempts to put the burden on sites boil down to changing this dynamic, recasting the Internet as if it should be appropriate to use as a daycare. Today it's big tech and porn. Tomorrow it's any writing that the the religious reich dislikes. Monday it's technical sites as they can help kids bypass restrictions. Tuesday it's international sites being blocked at the ISP-level because they don't bother with any of this crap.
We also need to remember the context here, lest we carry water for big tech's continued abuse. The main reason the surveillance industry is reaching for age verification (ie identity verification) is that harm to children is so far the only regulatory cause of action that has been found to stick. Big tech wants this, so they can continue on with business as usual abusing adults' psyche and personal information. Where what we actually need is to stop their abuse for adults as well - eg data privacy, anti-trust regulation to open up their services to competing clients, and at this point probably straight up regulation of purposely-addictive "algorithmic" feeds.