Earlier quoted context omitted.
You can choose something bad but still not have better choices available. If it's their best option are they allowed to complain then?
Yes. My understanding of "working well below market" is that it by definition means there are much better-paying jobs available to them, no?
But that's not the case, the market for the output of authors cannot sustain living wages, there is no 'market wage' to make. If you look closely at this and other creative professions, that has always been the case; there is always more people that want to make a living with creative work than there are people that want to pay well enough for that work so that the creators can live.
This is structural and unlikely to change barring something like basic income. The usual answer given to aspiring creator is both to generate the income you need to live in the service industry, say as a waiter, and also to be your own agent and pimp out your professional services yourself.