In another comment femto113 points out that provided there's enough credit card fares drivers can keep all of the cash they receive, with Uber taking their cut

In another comment femto113 points out that provided there's enough credit card fares drivers can keep all of the cash they receive, with Uber taking their cut via the credit card transactions. (However, it looks like Uber's cut is 20%, so it doesn't look like there's enough to make this balance out completely.)