I recall a wonderful video about freelancing called "f*** you, pay me", and I see there's an entire platform dedicated to it: https://www.theverge.com/22684237/fuck-you-pay-me-lindsey-lee-lugrin-decoder-interview

This, and being a freelancer myself, is one of the reasons I refuse to collaborate with artists without paying them - it freaks me out how many I've encountered who are surprised to be dealt with fairly and aren't sure what to do with themselves...