Within the caveat that this is a US-centric board and hence the answers are likely to be predictable, I would appreciate knowing how native Colombians (and other South Americans) deal with propina when it is automatically added to the restaurant bill.

While I am happy to voluntarily tip a waiter / waitress if I think the service warranted it, I resent it when a tip is added to the bill, without my explicit consent. Tonight I encountered such a situation; I do not speak any Spanish and the restaurant staff claimed not to speak English. However, they understood that I was unhappy about the propina line item, and gave me a revised bill without propina.

I would simply like to know how the locals handle this; or has gringo culture conquered the world?