The way they do this in Europe is that an enterpreneur buys a fleet of cars and then gets a visa for a number of folks from Bangladesh and other areas who don not own any of these cars and ride them in turns (they also sleep like 10 in one appartment but that's a different story). The owner gets the money and distributes them to the actual drivers. Uber says they are innocent as they are not in an emplyer-employee position with any of these drivers.
This model worked for the fleet owners so far because the Saudi gave enough money so that both (1) the customers were happy, (2) the cash from the ride could be divided between owners and drivers in a way these drivers complained only to a certain extent.
But the last two years (the only profitable ones) are much worse, both for the drivers and fleet owners. There is still sunk cost in there, but once the cars get old enough they will need to think well whether to buy/lease the next batches.