Recently one of the last controversies that reached spanish news is that some businesses are starting to refuse accepting the "sharing of a bill" when it comes to restaurants.
Let's say we are a group of 4, we drink 6 beers and get 1 croissant while we are at the table.
Person 1: 2 beers
Person 2: 3 beers
Person 3: 1 beer
Person 4: 1 croissant
It is common in Spain for people to ask for a shared bill, therefore each one paying only for whatever they have consumed, instead of 1 person paying for everything and then them managing the sending of the money privately.
For me, even as a spaniard, it is absurd to argue about this, it's not something businesses should take care for you, however there's many people also saying that if a bar/restaurant rejects the shared bill option, they would not come back.