I think you established too broad of a scope for discourse to be within the parameters you were hoping.

Immediately upon reading your comment, I thought about the general overprotection and over-supervision of kids which leads parents to drive their kids everywhere, prevent them from learning to use the subway on their own, or even live in cities. But what I think you were getting at is more about smaller hypothetical physically analogous places, but it's hard to think about what those places are in real life without relying on assumptions that may be more likely to occur online than in any significant concentration in the real world.

Imo, the most threatening place for kids to be in real life in terms of external factors, day to day, is around cars, bullies, bad actors within the family, and then maybe church/sports teams, but all of those are usually safe unless they're not, you can't realistically do anything productive about that without sacrificing their development as a human, except prepare them and guide them.

Online, it's just a whole different beast, and I'd think it would be games and social media, anywhere a gaurd would be let down, but imo the greater threat isn't criminality as much as it is nearly every other aspect except basic chats.