In my junior high they had a mysterious urinal pooper. They spent months trying to catch the culprit. They even resorted to a $25 reward and a little campaign in the morning announcements. Then it turned out to be a handicap student who couldn’t bend his knees. The posters and campaign quietly disappeared without a word.
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.