[xycodex]

Bad idea. Cash is the ultimate failure mode for on-site payment systems. What if the internet/phones went out? What if I'm visiting from abroad and my card is declined for potential fraud?

[hobarrera]

Lots of places already fail to generate invoices with no internet/electricity, so there really no new issue here.

Besides, I expect countries like Denmark don't have power/internet outages as often us we do in underdeveloped countries.

Also, you can notify your bank if you're travelling abroad so they don't reject anything. It's actually mandatory for some banks.