As i said before, i think it's a lame ass plan to force people to "take care" of the little ones while they get paid for them. Probably thinking that mister humans won't realize it until it's "too late" to change mind, which ironically there would never be a "too late", unless the mister human decides to really keep it, but we know how the yukkuri world works, if someone feels offended or doesn't want this shit, they'll smack the parents good and take back their money, if not kill them all and take the money.
They are more dependant of the mercy of the humans than anything else, reason why it epically failed 2 of 3 times