the answer is: people. if you feel you're not getting paid enough for your contribution, try 1) negotiating for more (& Union) payment (viz. residuals, which can become fairly substantial), 2) talking to either the artist in control or whomever is paying you, if you've got nothing to lose but the gig. many session players feel fine about simply raising their pay-scale, etc. all of the above kinda presumes that the sessioneer is not requesting more so they can disingenuously drive a personal money/power-grab, but because they actually know what they're contributing, re: an original part that colors & alters the arrangement sufficiently enough to be considered writing. (i'd say that, normally, that's someone who understands the sense of "ownership" that very often accompanies writing original material). but their abilities to be self-critical, ethically aware & knowledgable enough about music & music rights oughta be fine-tuned-enough to avoid money/power-grubbing due to overblown and/or "entititled" views they may have of themselves. again: many session players feel fine about simply beginning to raise their pay-scales (& thereby residuals, etc.), when they become somewhat indispensable to a musical employer who's doing (or might do) "hot business", sad-lol. ymmv.