I imagine that on a more free market economy probably Ubers would have QR codes, username handles, or some other way for you to just scan your phone (or type a code) near the door of the ride-sharing vehicle and the driver agree to the ride in the spot. This would be very nice to reduce queues and traffic at airports or other agglomeration places. It just doesn't make sense to wait 5-10min at a large airport like SFO, JFK, LAX, or ATL for a Uber ride while you see just many people being dropped off in front of you. This only happens thanks to the taxi monopoly.

It'd be better for everyone if you could just walk in any car in these scenarios.