In the case of therapy, there is a LOT of social conditioning that primes people to give up power in therapy. In some parts of the world, therapy ideology and concepts are ubiquitous and part of popular culture. The media hammers home some of these concepts to the point where it's basically social engineering. Therapy is also part of the healthcare system. These factors and others drive people into the system and into a position of subordination, because your "mental illness" ain't gonna heal itself, and therapy is the only way, etc. Even smart, autonomous people can be manipulated if the messaging is insistent and pervasive enough.