Why are men with facial deformities and twitchiness allowed to be cashiers, forcing me to vomit the food I'm buying?
Because everybody needs a job, that's why. If you don't like it, go someplace else.
Intrinsic Random Event
You don't eat the food while you're at the cash register, do you? Most people go home and put it in the fridge, and come back to it later. You'll just have to get used to the idea that ugly people exist, and that there are horrors in this world that would make you vomit up your entire digestive system. Don't be a pussy.
Because they are human too and need to make a living
You are an unpleasant, cruel person.