Age restriction puts the burden and punishment on citizens.
Your proposal to punish parents does the same.
How about a solution that puts burden on corporations for once?
That's great messaging, but what exactly are you materially proposing that's different?
If you make corporations liable for minors using their product, they're just going to require identity verification to use their product, and we're back to effectively the same proposal, right? Unless I've misunderstood you.
Because corporations don't have children?
Incentivizing parents to parent aligns the obligation, agency, and responsibility. People who don't want that level of responsibility can not have children.
Bingo. And now GP should go look who is behind age verification and ponder why they'd be pushing for this if it didn't benefit them.