Jumping in on this without knowing anything about the business model, but why not just ask all of the drivers to pay $35 (for example) one time to do a bg check / insurance check?
The higher fee to drivers is not about Uber's underlying fixed costs; a simple fee or holdback on the first commission check would suffice. The purpose of the higher fee is to make more money of off the driver's to make Uber's balance sheet look better.
Basically, it's an indication that Uber's finances are a lot weaker than their lofty valuation would suggest.
Right? I guess there would need to be some mechanism for updating them however. You don't want someone to get 'certified' and then get a record, but it be invisible.
I guess an ongoing rate is necessary for ongoing updating.