It appears that replicants can live on Earth and move freely but one needs permission. The hookers (owned by a human "pimp"?) can ply their trade. I guess Sapper Morton was a prohibited model? (The hooker asks K if he will kill her and he replies, iirc, it depends what model number you are.)
I do not know what the legal protection enslaved people had in the south -- if it was illegal to murder your own slave, I suspect that the owner was rarely prosecuted and if you killed someone else's slave, I bet you owed them the value of the slave.
I would guess that replicants has even less protection. In one of the short films made before BR-2049 came out, Wallace commands his servant to commit suicide. The people witnessing this were not very happy about it but no one discussed legal prosecution for what was in effect murder -- I think they objected to the replicant itself but Wallace was demoing a "safe" replicant so that he could I guess sell them on Earth.