Huh...I actually did this when I got out of a developer bootcamp in 2014/2015. I come from a family of lawyers; redlining a contract is second nature. Data point of one, but I think it's more a cultural norm - there's a strong norm in American society, in particular, against negotiating. Funny how well that works out for the people who control the capital and don't have any issues ignoring that norm. They should be illegal, but more people should start more conversations with a negotiating mindset as well.