Earlier quoted context omitted.
Regulating the companies also socializes the costs of implementing age verification measures. The correct solution that does not do this is to put liability on the parents.
Liability? You want to make give parents fines for their children accessing Facebook at a young age?
So if your goal is for the state to decide what is good or bad for children, then yes, giving parents fines when their children access 18+ content will motivate those parents to parent their children. That will be an effective way to achieve your goal. Other policies have issues with externalities (ignoring the inherent externalities of creating liabilities ex nihilo, which will exist no matter what policy you choose).
If you believe that parents should get to decide what content their children, then like me, you would oppose any kind of legislation with this goal in mind.