That's a good question. One problem is that my skills have improved, but so have the skills of others, while the overall amount of available work has declined. I'm a double bassist, and when I started playing, there was a shortage of us, but I'm not sure that's true any more, and the caliber of players has increased.

I think one thing is that $100/player is a kind of psychological "anchor" that people understand, and that is easy to negotiate. By the time I receive the offer, the bandleader has already negotiated their fee with the client, and now has a fixed budget.