Because power differentials do not invalidate consent? Power differentials do not indicate coercion and people are fully capable of consenting even in the presence of power differentials. We've gotten to the point where we equate potential for abuse with abuse. Its a little ridiculous.

Surely you agree that sometimes power differentials can invalidate consent. Can sex between a police officer and another person that they have placed under arrest be consensual?

I don't think a power differential in itself invalidates consent. In your example I would say the scenario of an arrest is inherently coercive. But this is just quibbling over semantics.

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?

I don't think so. With a police officer/arrestee relationship, coercive power is already being wielded. Being detained is inherently coercive. Any "request" from an officer acting in an official capacity is done with the implied backing of state power, and being arrested clearly establishes the coercive relationship.

But employment is transactional. There is an expectation that the agreed upon transaction will be upheld. A request that falls outside of the transaction, e.g. your boss asking you out, does not inherently imply economic coercion (whereas a request within the employment transaction does). But specifics of the context can alter that, i.e. wording of the request or specific context can imply coercion.

Consent is the minimum required for sex to not be rape. That doesn’t mean the relationship is ethical.

I don't know of a scenario where I would say a relationship is unethical if consent is satisfied. What scenario do you have in mind?

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.

Some of those are fair points (scenarios issues involving external people), although considering the context of this discussion I was referring to ethical concerns between the two parties involved in the relationship. Coercion of various sorts negates consent in my book.

I’ll add to the list: doctor-patient, lawyer-client, judge-lawyer, judge-litigant, social worker-charge, police-detainee, prison guard-prisoner, etc., even in contexts where there is no actual coercion. There is more to relationship ethics than consent. You have to consider the ethics in the context of the other relationships between the parties. Lawyers engaging in relationships with their clients is in fact an ethical violation, regardless of consent, because of the possibility of or appearance of abusing the lawyer-client relationship. Relationships necessarily also affect third parties (other partners, coworkers, etc.) Those effects must be considered too. People owe each other (not just partners, but third parties) more than just not committing rape.