I work with quite a few restaurants and cafes in Melbourne, Australia. One thing that my customers would really like to see is more flexibility with the modifiers:
Optional modifiers - right now, every time we select an item with a modifier, a pop up appears. For example, if I order a cheese burger without any modifications, I need to close the pop up every time. This gets annoying in a fast food environment as there are certain items only require a modification only sometimes. It would be much more user friendly if the pop up was compulsory for chosen modifiers, and no pop up for option