That is almost certainly correlated to specific "ability" in the task they are getting paid to do on average although you could argue to what extent.
The subtext here is "things would be more fair if you let me be dictator and pay everyone based on my subjective perception of their ability which is more fair than the collective decisions of a free society."
Because the article includes education, let's have a smart kid with good education from a poor family: They still won't study abroad in europe; won't take a year to work on their startup; any startup won't be financed by friends, family and fools; won't be introduced to the CEO of some company by his uncle; won't be meeting people on the golf course; they probably even studied longer and are missing relevant job experience because they had to finance it themselves.
If they are smart they can make it further up, but the inhibitors add up and they won't make it all the way.
Yes, but they can make it some part of the way up, putting their kids in position to go a little higher, and so on. Success is largely social, a multi-generational task, which is why parents push their kids so hard: college, and then elite college, is the main step that breaks the cycle. Maybe gen 1 goes to Stanford and joins a FAANG. It's gen 2 who will have the CEO uncle and a shot at founding a FAANG.
A simple and straight forward solution is that every job is required to have a union available by law, we remove most of our inequality to the point where fighting about who has multi-generational privilege is no longer an issue. One step further is worker ownership of the company they work for. Example, instead of being publicly traded, Facebook should be owned by the people that work there, 1 share per employee. It would result in a much healthier environment and less psychopathic corporate behavior.
Hence the momentum to address the monstrous differences in opportunity that have been created after many, many generations of treating particular groups of Americans as second-class if not outright sub-human.
And it seems weird to want to pay back a debt racked up by an ancestor. Or not even an ancestor, just an ancestor of someone who looks like your ancestors. Anyway, I don't think you help oppressed people like that, I think you help them by going in there and teaching and being positive about the real opportunities available - to go to college, get a job, earn a living. Live in a bougie neighborhood, maybe.