Earlier quoted context omitted.
Can I ask something that will sound incredibly naive? How complicated needs to be an IT infrastructure that lets you book a taxi via an app and pay the driver? Is it really something to throw billions at each year? Sometimes I feel these companies are throwing billions in IT simply because they're expected to be disruptive technology companies, and not for real technical reasons.
Uber as a product is very technologically complex, mainly because of the scale it operates at. You can read about some of their tech at https://eng.uber.com .
Also because when Uber was young, it was not motivated to seek profits or consider expenses, it was just growth at any cost. Once that work culture is established, it can be hard to shake.