If a company has people doing hundreds of taxi rides globally per day, you can bet they want good invoicing/expensing. They'll get contract deals with taxi companies in their most major areas specifically to get the invoicing (if they can beat down the total price too, that's a bonus, but actually sensible invoicing saves them money because they don't have to do mountains of expense handling). Thus, doing one deal with Uber and getting a couple of dozen cities covered is great (note: "countries" is misleading, because often they only operate in one city in a country, and amazingly, sometimes people have to leave that city to get to work).
So the point is, Uber/Lyft/Addison Lee, or indeed your local i-own-a-mercedes-and-a-tax-license driver are all great when you can get them to centrally bill/invoice for the work they do. If they're handing you paper receipts on every journey, even if it's 10-20% cheaper than the alternative, then they won't get the business.