It seems like most replicants are part of a rebellion. K is not obedient. Luv lies to Wallace about killing Madam in self-defense, implying he would not have wanted her to kill her.
Perspective good sir.
1.) Wallace has apparently created scores of replicants. I believe he said "millions", and while that may have been hyperbole we can assume that he's created a lot of replicants, and given the government hasn't shut him down, we can assume they're all sufficiently obedient. The demonstration replicant in the short film introducing Wallace makes it clear just how obedient they are.
2.) You could literally count the rebellion members on your hands. Looked like about 20 of them in the room, fam. There's no reason to assume "the rebellion" constitutes any more replicants/humans than we see in that room.
3.) K was obedient and almost machine-like until the idea that he may be special changed how he saw himself and the world around him.
4.) Luv was clearly designed to be unique and Wallace says so more than once.
So yea, the movie focused on the 0.1%. Don't miss the forest for the trees, as they say.
That makes sense in the long term. But the cost of waiting 14-15 years for fertility, managing, storing, and caring for them in the interim, vs. several months for a full grown person seems to be a losing proposition for several generations.
But natural reproduction requires no enhanced or special technology once it is an option. It requires no special facilities. No special equipment or materials. No expensive transport to get them from the creation facility to X off-world colony to work. It will happen on its own and next to no cost. While there is a time cost to waiting for said replicant to grow up to a working age, once you reach a certain volume of total replicant slaves it doesn't matter much. The young, strong new workers added to the workforce will outnumber the old, injured, and feeble.
see: actual North and South American slavery. Fertility of slaves was a critical aspect of their worth calculation. The costs incurred vs purchasing new, grown slaves were considerably lower and the process considerably simpler.