That's it exactly; surprise egg videos get repeat views, kids open them up and just hyperfocus and/or zone out on them for hours on end; it's low energy watching. Give them something intellectualy stimulating though, and they'll have brain drain after a while and be too tired to keep watching that kind of content. Bad for revenue, it's better to have them accrue those minutes watched counters all the time.

There is absolutely no technical reason this problem could not be solved. It is not a technical issue. It is a human issue. Just like most issues of modern society.

Is there an existing service I can pay to curate YouTube?

Is it allowed to sell a YouTube app that only offers curated content?

Right. I.e. it's a hard problem. Technical problems are the easy ones.