Imo merchants will most likely always have internet, even in remote locations like a beach or a music festival. As a client, you could simply carry a card, ring, or even an NFC wristband and tap to pay then. Or using a phone and mobile device with Bluetooth, as in this case, might be interesting if you're abroad and don't have roaming. Additionally, it could potentially be even better for privacy in general, since no internet is involved at all in the transmission.