Uber is just as capitalist as any other company which requires its workers to buy their own tools (which is rather a lot of them). The trick is that those tools don't actually allow you to perform the work in and of themselves - you still need Uber for a steady source of passengers and for regulatory protection, and the only way you'll get that is wage labour.

Uber's "means of production" are its data infrastructure, not its fleet of cars.

In old fashioned industrial revolution terms the infrastructure is the loom, the driver network is the cloth it produces.

I think that's what's commonly referred to as the sharing economy.