Institutions, rather than individuals, as masters, makes the master - servant relationship far more consensual. You choose to serve others in the context of a j

Institutions, rather than individuals, as masters, makes the master - servant relationship far more consensual. You choose to serve others in the context of a job, and when that job's over, they no longer have any power over you. A personal master servant relationship carries over to places where the servant may not consent to. It's a personal relationship, meaning it encompasses your entire person. It's far harder shed that relationship than it is a job. Making the master role institutional, and one where the person filling it is interchangeable, also means that it's meritocratic. Anyone can fill the master's role, because it's ultimately about how useful they can be in that role (e.g. by spending more money), rather than about them having a personal status of 'master', which they need not contribute value to maintain.