You would think so, but I know many players who are terrified of losing their local game or their social group and allow themselves to be subject to a considerable amount of abuse. You can rightfully say that it is their fault for not having the courage to go without a game or friends. This is a reasonable concern I have brought up to some of them before. But you would be wrong if you think a 'Yes' from your player is always consent without duress.
I've seen players say 'Yes' for all kinds of terrible reasons, twice from women who thought they would be ostracized if they said no, more than a dozen times where players after the game talked about how much they hated it behind the back of others even though they gave a clear 'Yes' when asked, and once with an underaged girl who had no business being anywhere close to mature subject matter and said 'Yes' because she had no other friends.