Each views the other as having power in many cases.

Clients are seeking out something from the therapist and believe that the therapist has the power to give them what they want. Love. Acceptance. Whatever. This is why so many emotionally unwell people go down dark paths in therapy. They think the therapist knows best.

Therapists know that the client has the power to stop paying them so the therapist oftentimes bows down to the client and won't even say "boo".