You hire a contractor because they know more about the work than you do. That expertise makes delegation useful, but also makes it hard to judge whether every recommendation serves your interests. The person doing the work knows things the person authorizing it cannot easily verify.
Principal-agent problems arise from this combination of delegation, differing interests, and incomplete information. They do not require either party to be dishonest. A contractor and client can disagree sincerely about quality, urgency, or acceptable cost.
Control has a cost too
Monitoring can reduce uncertainty, but it consumes time and may interfere with the work. Incentive payments can reward a desired outcome while encouraging neglect of aspects that are harder to measure. Detailed contracts still leave unexpected situations to someone’s judgment.
The relationship may also contain several principals. A public official answers to elected leaders, professional standards, and citizens whose preferences differ. Treating one instruction as the sole objective can conceal those conflicts.
Good delegation therefore involves a workable combination of authority, information, incentives, and trust. The useful question is which decisions the delegate can make independently and how the consequences become visible, rather than how to eliminate every difference between the people involved.