I do not disagree that there is A LOT that Apple could, and should, be doing to enable parents. The problem that we have is, that if a vendor, like Apple, just decides to continue to have broken systems, there isn't a way to compel them to fix the problem outside of legislation. And, because most people in the House/Senate have a complete lack of technical literacy, we get situations where they define things poorly or special interests get to set those definitions in their favor/for ideological reasons, rather than to make good policy.
We agree that legislation won't work because legislators aren't competent.
But you claim that only legislation can force behavior, and I'm pretty sure that if a few senators just relayed their frustration with broken screen time reporting to Tim Cook personally we could get some results.