... can they pay the driver in the car, or does the booker always pay?
I've never been in an Uber myself, but when I booked for my son I pay via the app. However, at the weekend I booked one for a friend, expecting to pay for it and sort it out later. This morning the credit card payment is showing as "pending", but my email receipt says "A temporary hold of £x was placed on your payment method . This is not a charge and will be removed. It should disappear from your bank statement shortly."
So I'm wondering if this means my friend paid the driver directly, if that's even possible. (I don't want to ask them, because that would be awkward).