Not JUST correlated with poverty, but likely to a large degree, I agree. Ideally, kids would get a maximum amount of quality time with their parents or siblings instead of being parented by the internet. Wealthier parents parents, I suppose, would be more likely to have the free time (or that of paid help), emotional availability, educated tendancy to read and develop and understand of the importance and structure of shared time, healthy established family norms, and genes. There's a lot going against poor families, and it's not getting easier.

In addition healthier people could be wealthier.

The causation is almost certainly reversed: https://www.brookings.edu/articles/the-growing-life-expectan...

Yes, money is also a factor. You can see some data in https://substack.com/home/post/p-140838494 by the same guys.

I am pretty well off and I am very guilty of letting my kids overuse electronics. Plenty of my friends are the same (we've discussed it).