What's the fundamental difference between an employer / employee relationship (where economic power can be wielded) and a police office / arestee relationship (where legal power can be weilded)?

What makes the latter "inherently coercive" but not the former?

Aren't these just different degrees of fundamentally the same thing?

Adulterous relationships. Incestuous relationships. Relationships between professors and students. Relationships based on economic or employment coercion. Relationships in the workplace, even if not coerced, that could result in favoritism prejudicial to others. Again, consent merely distinguishes rape from non-rape. There are many degrees of wrong and unethical conduct short of the outright criminal.