A lot depends on who is producing the porn they are starring in. How much money they'll make, what is involved in the scenes, etc. There are good producers and bad ones which is why you should always know who you are working for/with! Some of these actresses have no idea what they are getting into beforehand, the facialabuse guys tell their actresses it's a "rough blowjob scene" when in reality it is much more hardcore than that. Then when the girl becomes hesitant during the scene, they tell her they wont pay her if she doesn't finish. You honestly cannot tell me that no person in porn has ever been pushed beyond what they were comfortable doing because I personally know people this has happened to. Hell, there are entire porn sites dedicated to doing exactly this. Just because you get paid to do something doesn't absolve your employer of any mistreatment. All jobs are exploitive because you need money to survive in this world and making porn is no different. I feel sorry for the guy who mops up people's shit at concerts. It doesn't matter how well he gets paid, his job is still shit.

Edit: Also, you say she could easily get another job. Maybe this was the scene that caused her to do just that. I remember listening to a Max Hardcore interview where he bragged about how many girls quit making porn after they do scenes with him because they are so emotionally traumatized afterwards. He also said he likes to get girls that have never been in porn before because they haven't learned to say "no" yet. Although this is an extreme case (the man is in prison for making porn), I know some other porn producers have the same mentality.

I would also like to add in that anyone with a camera and Internet connection can be a porn producer.