[downerending]

I used to wonder about this when I was younger. Now, older, I think the answer is that "senior" people are paid more, etc., because they can be trusted to generally tow the rope in the direction the company wants. They're usually not disruptive and usually do act professionally.

None of that has much to do with skill. As for skill, on average they're somewhat more skilled, but it's a smallish effect.

I do happen to be more technically skilled than most around me, but other skills matter more. I can avoid needlessly ruffling feathers. I can often foresee that a project will crash and burn months or years in advance. I can talk to people going through personal crises. This is all learned over long years.