I’m not convinced by your quick conclusion. Apparently, object density is about 1.7 times as high in deprived areas and tagging depth is 3.5 times as high in more affluent areas. However, instead of investigating further, you brush away the higher tagging depth with a few sentences and decide that object density is the marker for mapping quality. Could it not also be possible that deprived areas have higher object density because they are simply more densely populated? In that case, the higher density of OSM objects would be due to a higher density of real features. Without trying to take that into account, the raw number of object density isn’t worth much. I’m not saying that the original assertion that wealthy neighbourhoods are mapped better is true, I don’t know that. But your analysis alone can not disprove it.