Hmm, I thought that at the end of 4 when discussing being short of money there was a conversation about how one of the other girls was reluctant/resistant to the situation.Thing is that, up until this episode, it didn't seem like she was really doing much forcing. In ep 3 we learned that Sarah and Melanie were doing pretty well for themselves and both Riona and Camila seemed to enjoy their glory hole work, so it seemed like they were all pretty willing participants who didn't need much coercion.
It makes her push to try and get Maya, Ashley, and Mona involved seem a little desperate and arrogant from Quinn and it probably has more to do with her need for money more than this being how she got the other girls involved.
And yes in this episode we saw one sister hiding out and mid break down, one fleeing a professor and saying something along the lines of "I can't do it". Just because we aren't shown evidence of others being reluctant to whore themselves out doesn't mean that reluctance doesn't exist. We don't get to see everything that takes place in other rooms.