Sure, it doesn't solve the problem of child videos using other monetization channels like product placement, sponsorships and so on but don't let perfect be the enemy of good.
If we exempt them from your new rules, why?
We need to be very careful about Well Intentioned rules (or worse, laws) because they will be applied selectively and in ways the authors didn't intend.
Ban the commercialization of videos and images containing kids. No more child actors, singers, models, etc. Remove the child labor law exceptions which have been given to these industries.
it'd make movies better, anyway
If you're posting content to the public (i.e. random strangers), you're on one side of the line. If you're posting content in a controlled manner to people consisting of friends and family you actually know, you're on the other side of the line.
Posting privately for your extended family yes, but that should never be posted publicly.
The issue is trying to ban an innocent thing - photo of a kid in state normally seen in public vs "making kids perform for camera, encourage them children to form participate in parasocial relationships with the audience".
No kid ever build parasocial relationship by having photo in family album, even if public. And photos of kids are as old as photography.
One could make regulations about monetization of such things I guess. Monetization does not just happens randomly. You have to enter into contract with social network to send you money, you fill taxes. That could be workable, theoretically.
It's important to protect the private lives of our children. But it's very challenging to draw clear, enforceable lines in criminal laws and social media terms of service.
Second step, zero public posts involving children, maybe with some narrow carveouts.
"I'm sorry mister, but we can see chidren playing in the park at 44:28 in the hour-long documentary you've produced, so we had to remove the video."
/s
Implementing your proposal is also unreasonable: before one took a photo of their spouse in the park, they would have to clear the background of all persons or get their explicit consent.
If there was a protest outside my business, could I post a photo of the crowd online? What if it were a riot?
What if, as I and a large crowd were peacefully leaving an event, I lifted my camera above my head and blindly took a photo of the mass of people shoulder to shoulder?
Many places have laws which would prevent someone from taking a photo of an individual and selling copies of that photo without the subjects permission; but these laws don't usually apply to someone in the background or a crowd shot, and they don't apply to non-commercial use or some commercial uses, including journalism.