> For example a kid from a loving and conscientious poor and illiterate parent may receive better parenting than a more perfunctory well-off parent - and yet the latter will undoubtedly be ahead by the time they reach kindergarten.

Undoubtedly?

> The issue is not so much, I believe, in the "goodness" of the parenting, rather, it is in the richness of the environment.

In the US at least, there are free yet rich environments. If you're poor, you do have to get out of the house and seek them out.

So, what definition of "better parenting" are you using?