Empirical data shows those from upper middle class families tend to do better than those living near the poverty line. Seems pretty well documented at this point.
Pointing out that people who are doing well now tend to do well in the future is not a useful observation. My original point in this discussion was that removing the tests actually hurts people who are not doing well now, since they have fewer opinions to game the system and having an empirical and objective test of their abilities is the best (and cheapest) opportunity to stand out.