I work in hospitality, and if there was one group of people that were the worst to serve, it would be vegans. They'd never tell you before they got here that they were vegan, and yet still expect a full meal at a place that does a fixed menu

You'd at least expect somebody who has such a strict diet to check the menu beforehand and tell the place. We don't have the same problem with FODMAP or coeliacs. Just bloody vegans