The issue is that currently, adding restrictions to what minors can do is expensive, both economically, and politically. It requires the cooperation of a lot of non-government appointed people, and many of them could (locally) sabotage the restrictions.
This limits the restrictions to those with incredibly broad support. Keeping a lot of agency with families on how to raise their children.
Digital age verification, if implemented well, is easy to enact, and hard to sabotage without being noticed. That enables restrictions that 49% of people disagree with. Heck, it enables restrictions that 49% of Congress disagrees with. That could be 60% of people disagreeing.