[GreedClarifies]

Of course they have those barriers.

The incentive for managers is to promote.

Perhaps if managers had budgets of dollars instead of budgets of headcount then the imbalance wouldn't be as large, but AFAIK companies do not do that except at very high levels.

[frankreyes]

Having a dollar budget would make the imbalance worse unless ideally they don't get away with moral hazard. The issue is usually having managers taking all the benefits and none of the risk, and that's bad.