I'm always amazed when servers mess up when it comes to settling the bill, leaving you sat at the table waiting way too long, especially if the service has been good apart from that. It's the last bit of the experience before you pay and tip.
We went to Earls recently and you could pay for your meal via the unique table QR code and online app, it was WAY better (but still had a personal touch as the server came over and thanked us after we had). The future is probably going to be ordering via those as well, and someone will just bring the food to your table (eventually a robot, because of staffing issues).
I've only ever walked out after we'd waited an hour and 45 minutes, with young hungry children, and the "you're order is just being finished" we'd been told for the last 45 minutes changed to "they will be starting your order real soon"