Now what if you Isekai as a slave instead? What are you gonna do? Find a "good" owner?
If I'm a slave, then I obviously am not able to choose my owner. I don't have this kind of freedom, that's what it means to be a slave.
Try to be free ASAP? and how could you do it?
It's probably either impossible, or extremely risky and most likely suicidal. That's why there would be other slaves there in the first place. Otherwise, they'd have already escaped.
So, I'd do the only reasonable thing I could possibly do. Try to be meek and obedient so that I don't get hurt much. If I'm lucky I might get a master that doesn't abuse me too much and I'd live with that.
... And, of course, if I got one of those masters from isekais that offer freedom to their slaves, I'd definitely take it. No reason to be forcefully subservient for live if I can help it.
... Unless slavery happened to also protect me and make sure I stay fed. Between having to find a living for myself as a former slave while having no backing to speak of, or having a kind master that will keep me fed and doesn't abuse me, I might choose the latter if I'm not confident in surviving on my own.