I think a couple people have already said this, but a really good question is how would they force people to microchip their dogs?
People would just buy a microchipped dog and bitch and then breed a bunch of puppies that they wouldn't report and sell those to whoever wanted an un-microchipped pit.

One saggy boob says to the other saggy boob, "If we don't get some support soon people are going to think we're nuts."