It's also laughable to think that anyone would be so stupid as to allow a person with no real involvement to convince them that they should give birth when the thought otherwise had not crossed their mind!
I would love to agree with this statement, but unfortunately there ARE people this stupid (and greedy) in this world that they would have children for the sole reason of getting money.

They might convince themselves that it was the final decision maker - the thing that "tipped the scales", but it does come down to greed.
Back to the sterilization part: when I worked as a surgical tech (almost 12 years ago - wow!) we wound up having to do an emergency laparotomy on a 16 yr old girl due to an ectopic pregnancy that had ruptured. This is bad enough that she was only 16 - but she already had 3 children! According to her records, her first child was born when she was 13, that means she was pregnant when she was 12, and had pretty much gotten pregnant every year afterwards.
I don't know that paying for sterilization would have made a difference in this child's life. If her parent(s) were so lacking that they couldn't step in after the first pregnancy and go to a health clinic to find birth control, they might not have been educated enough to
know about another option.
On the other hand, many people (although definitely not all) have more kids so they can get more money from the government without working. So if her family was this sort, then this incentive would have appealed to them.
Overall, I do not think there should ever be an incentive given for people to have children. There are too many little ones in this world already that are not wanted. A couple should make that decision on their own, having a child for love.
Incentives for NOT having children is actually a pretty good idea. If a person really wants a child, they are not going to be swayed by this bribe - and the child will definitely be wanted. On the other hand if a person takes the incentive, then they wanted the money more than a child- so it is better that a child not be in that home.
I hope that made sense.