When I last visited Argentina Uber was using the official exchange rates which were just fantasy numbers. As soon as you match with a driver they’d message you and you’d negotiate the cash price. Then the ride in the app would be cancelled.
Uber didn’t mind because they were still getting the ~$1 or so cancel fee for basically being a messaging app.
I use a scoop of rye flour (30g) mixed with all purpose flour (70g) in my starter. The rye flour is like miracle gro for the bacteria. In my country it’s also cheaper than all purpose flour.