The biggest issue I see is two-fold:
(1) Someone wants to break a bill to leave a tip; and
(2) Someone realizes at the end of a meal that they don't have a card on hand (or that their card has been unexpectedly frozen...been there, done that more than once).
#1 is annoying; #2 is a potential problem. The "quick fix" to #2 is if someone else in the room is willing to swap, say, a $20 bill for an $18 charge (or something like that)...I've been in the reverse of this at the border and made a small differential (i.e. $10 USD for $10 CAD) on offering out-of-country passengers change to clear the agents with. But if there's nobody handy, that could be an issue.
(1) Someone wants to break a bill to leave a tip; and
(2) Someone realizes at the end of a meal that they don't have a card on hand (or that their card has been unexpectedly frozen...been there, done that more than once).
#1 is annoying; #2 is a potential problem. The "quick fix" to #2 is if someone else in the room is willing to swap, say, a $20 bill for an $18 charge (or something like that)...I've been in the reverse of this at the border and made a small differential (i.e. $10 USD for $10 CAD) on offering out-of-country passengers change to clear the agents with. But if there's nobody handy, that could be an issue.