I work in hospitality at the moment (part time while I finish my degree), and I can add to the list!
13. It irritates me no end when we have a massive line of people waiting to be served, and the person I'm serving was in line for a good 5 minutes, and we have menus up EVERYWHERE, including at the front door, along the entry hall, as well as at the register. Instead of using the time they are waiting to be served to decide what they want, they wait until they are at the register to make up their minds, and then they take about 20 minutes to do so. And you can't do anything about it!
14. When you take someone's order, read it back to them, they say "yes, that's correct" and then they change their mind; so instead of dealing with eating what they ordered, they wait until it arrives, then whinge at the manager that "this is totally NOT what I ordered, blah blah blah" and I get raked over hot coals.
15. The system we have is - we take your order, we seat you at a table. That table has a certain number according to where it is in the restaurant. We write your table number on your docket and it gets taken out to the kitchen. IF YOU MOVE AFTER THIS, YOUR FOOD WILL NOT GET TO YOU! But of course, sheeple know best and they decide to move anyway and then wonder why their food hasn't arrived after an hour.
16. When the restaurant is at capacity - I mean, standing room only, - and the table you're taking your guests to has only just come free and is the ONLY one in the whole restaurant that is free, and they say, "I don't like sitting here. Can I sit somewhere else?" and you want to say, "Sure. The floor's clear." or "No, use your eyes, dumb@$$, this is the only table that's free" or something like that, but instead you have to take them back to the lobby and wait for another table, which can take a good 5-10 minutes sometimes, and then they bitch at you because it took to long for them to be seated.