[nchie]

Is it really abusive if it's up to you to choose "Work at company X, make ~10% more but you have to be on-call for 1 week every 8 weeks" vs. "Work at company Y, make ~10% less, but never be on-call"?

Honestly, I'm not even sure how it's even remotely possible to draw a parallel between slavery and that. When negotiating a salary you'll have to take these things into account. Not worth it for the pay? Find another place to work. Jobs do grow on trees for people in our industry.