You see, in an effort to make everybody happy and fluffy and lovely we have to invent ever greater controls to curb the undercurrent of unpleasant opportunism that lies at the very core of humanity. It's the drive that helped us survive and once upon a time the procreative part of that drive was necessary as new members of a true community would balance the loss of experience at the top with vitality and vigour at the bottom. Also, high infant mortality rates meant that over-breeding was essential; but in-bred redundancy is a genetic imperative we can no longer afford.
Trouble is nowadays, not only do we not lose enough of the little fuckers early, we keep children dependent until their mid-twenties by extending their aimless education and kidding them they're all university material. Then they can't find jobs anyway, so they go back to sponge off the very parents we helped to incentivise in the first place. Then they get bored and end up, inevitably, becoming parents themselves and remove themselves, sometimes permanently, from the jobs market. Where's the point in that?
Child Benefit is a type of failed Ponzi Scheme that pretends to reward its investors from their own money or the money paid by subsequent investors, rather than from profit earned by the individual or organization running the operation. Or; invest in kids now and they'll repay that investment as taxpayers in the future. That model may have been viable in 1945, but it's nonsense now.
A Ponzi scheme entices new investors by offering higher returns than other activities, such as low-grade work. Perpetuation of the returns requires an ever-increasing flow of money from new investors to keep the scheme going. Or, the more sprogs you pop out the more we need to take from current taxpayers to continue to encourage the unworthy to squeeze out yet more sprogs.
People will breed anyway, whatever measures are taken to prevent it - I favour something in the water - but actually paying for the product is utterly ridiculous. Remove Child Benefit altogether. It won't stop the underclass from duffing-up, but it might slow them down a bit.