Corruption and power seeking are common among managers of businesses, and especially among middle managers. One way this power is most often abused is within the power structure of the organization itself by "misappropriating" promotions and pay. Controls are commonly employed to prevent managers from acting unilaterally to either hand out promotions and pay raises as favors to loyal employees or to game their way into undeserved promotions for themselves.
A popular control mechanism is to vest authority for promotions with someone other than the manager of the person under consideration for promotion. For example, suppose Alice reports to Bob. Bob would like to promote Alice and increase her compensation. The details vary, but a procedure might be for Alice and Bob to create a promotion packet that argues why Alice should be promoted, then this is sent for review by a committee of managers that does not include Bob, and ideally does not include anyone who manages Bob directly or indirectly. This committee decides if a promotion is warranted based on the packet.
This isn't perfect because Bob might still orchestrate trades—if the committee promotes Alice then Bob promises to approve promotions the committee members put forward—but this can be further controlled by setting explicit standards for how promotions should be made and have senior managers (ideally officers of the company) enforce the standards, either by checking every promotion if there are few of them or doing random spot checks if there are many.
Such systems generally work so long as managers are held accountable for real, measurable business outcomes and not internal, derivative metrics, since this helps keep them aligned with generating value for the business, and they will stand to lose by handing out promotions to those who are not qualified. If there's no accountability for outcomes, though, then such systems are likely to be gamed since there are no long term consequences for undue promotions.