This isn't viable because the systems these companies use to get the kids gambling is not obvious, even to a watchful adult. This is by design. Companies are also not obligated to give any information parents can use to identify this. Lastly, a lot of these games are free to get into, so the parents have no reason to know/ find out their kid is playing fortnite for example.
Again, these aren't circumstance, they are deliberate design choices to skirt the law and prevent potential action to stop it early.
When forced to choose, minimizing harm should always be prioritized over maximizing good. I more mean this in terms of utilitarianism, but even outside of that framework, improving things seems to cause more problems than working towards equity, and once equity is closer it is easier to improve things after.