Obviously this is about the power outage in Spain.
While normally, if a card declines, people would probably have to leave their IDs with the restaurant while they went to get a withdrawl from their bank; this is a power outage, withdrawls wouldn’t work. It would be silly to arrest people because of a power outage. So I’m assuming people just have to give the restaurant owner/management their identity info with a promise to pay?
And power outages shouldn’t affect buses, since they run on gasoline/diesel, but the payment system processing transit passes might not work. Do buses still get run during a power outage and they just let people on for free, or do they just shut down the bus lines?
On buses the card payment system is (usually) not real time. The card info is processed overnight. This assuming the network connection between the bus and the processing system is up. Mobile networks towers do have batteries, but only for few hours. Only in remote areas they have generators (I’d expect a few in cities but mostly not).