My first thought was “yeah but there are also things you can not undo like sending e-mail” but then I remembered there is a really nice undo send button now (that works by delaying the send a bit).
Sure there are things you can not undo, sometimes you do want to permanently delete something, but maybe with a bit of thinking a undo is feasible more often then one might think :-)
The rki (they are the ones tracking Infektion Numbers etc here in germany) is apperently Building an App based on Trace Together. This (german) article says TraceTogether is linked to your phone number though https://www.golem.de/news/corona-app-per-bluetooth-kontaktpe...
“This raises a lot of interesting questions about cash vs. cashless societies, and how in times of protest people may drastically adjust their usual economic behaviour.”
Also what happens when you dont have the option to “adjust your behavior”? Like at least in Germany payments above some amount I don’t remember can not legally be paid in cache.
Then you could get out at the current stop and let the next bus take you to the next one. I've seen this in New York where trains become 'express trains' Im shure other cities do this too.
Sure there are things you can not undo, sometimes you do want to permanently delete something, but maybe with a bit of thinking a undo is feasible more often then one might think :-)