I think you misunderstand, or maybe I do. Uber itself is as easy to use here as anywhere else, you just pay cash instead of pay by card. The system is still the same, fares are still pre-agreed etc.
Trying to pay by card or going to the airport seem to be issues that limit the service here. .
I understood that it's a mess. They may accept you; they may not. You have to carry around a lot of cash. Something that works well in other countries is a disaster here. Not worth it. Argentina can just stay in the Stone Age.