I've seen trust-based mate shops at hackerspaces around the world, and I've been told that the ones that have a credit system (even one that's not limited, checked, and that's not even authenticated) end up actually not having any significant losses. Like, anything from a piece of paper with people noting down unpaid mate purchases to things like android tablets with a webapp letting you note that you put in a bill of N euros and taken out a bottle of mate.

Friction from being able to pay right away seems to lead to "I'll pay extra later" thinking, which makes people either forget or miscalculate how much they actually owe.