My point is that such a limited amount of money is at stake that confirmations really aren't all that important in this example. I think most places would just accept the risk. Heck, they could have the POS alert the owners if anything fishy happens between payment time, and when you actually receive your drink if they are really concerned.

I really don't think this is as big of a problem as you are making it out to be.

People still wait for coffee? I order from the app; it's paid for and ready for me when I walk in the door. With a 3 minute confirmation time, this flow still works. If it doesn't confirm, then they corral me, I guess.