My point is that being enabled by default on all new devices 1) would also be fought by people very similar to you (if not you specifically), and 2) would not be effective if the enabled-by-default software is not effective, which would also require additional work that you and people like you would fight.

I do agree it could be done. I disagree with your characterization that it would be easy/easier, or that the current age verification efforts are entirely nefarious and not actually trying to work the problem.