Uber operates in: ride sharing, food delivery, bike messenger, corporate travel, freight, helicopter, and gig economy jobs, and more - and these are just the publicly launched products. Each of those lines has its own external _and_ internal products, with their own features, and their own regulatory burden. They each have their own cost structure and incentive models. They're live in over 900 cities across 85 countries, many of which have their own local regulatory burden such as NYC.

Then, on top of that, you've got 91 million monthly active users. Assume each one takes only one ride per month, and only 1% of them have some kind of issue that requires them to reach out to support - that's still 30,000 new issues per day many of which will require coordinating between both parties involved in the transaction.

Do they have more employees than they need? Define need. It's easy to hire above what's necessary to sustain operations when the cost of capital is cheap. More people can develop new products and grow margins for the business overall. But Uber is seriously far from "an app together with some driver administration" any more than Amazon is "a website with some seller administration."