> Would their drivers refuse to undergo them?

Refuse is probably a strong word here but I imagine significantly less people are willing to drive in somewhere to give their fingerprints for a background check than just entering a social security number in a web form. So there's more inherent friction. But then Uber needs to maintain an office (or a set of offices) in every city that provides convenient parking and some kind of fingerprinting system. So it puts uber in a business that they're not in and makes it harder for drivers to become drivers.