I think you’re missing how complex international operations and optimization are.

Each country has their own laws around what uber is and isn’t allowed to do. This needs to be formalized in code. For example you actually call a taxi, though the uber app, and the amount you pay is per mile, not a fixed fare decided ahead of time. To add to this complexity, some cities will have their own laws. What happens if you take an uber from town a to b, where each one has different laws ? A lawyer probably has an answer but the app needs to adhere to that. On top of that laws change all the time.

Optimization, well you can always optimize something. speed, costs, paths etc. In a way this never ends.

I think the part we interact with as consumers is a tiny sliver of the complexity those services have to build and operate.