Now working in the service industry I have a good chance to observe people.
Voices and appearances often don't match. Accents cannot be predicted based on clothing or hairstyle. Some large people have very quiet voices. There is a regular that sounds like Winnie the Pooh.
I have served tourists that know zero English. Pointing didn't work this time so they finally got out their phone and communicated through the advertised prices. There was also a mute person who came in and asked for pen and paper by mime and wrote down his order.
People are usually good. I was serving 2 people at once and they discovered they both wanted a 6 inch of the same sandwich on the same bread, so these strangers decided to share a footlong to save money. They took turns ordering toppings and only cut it in half at the very end.
Often when a person is working the front alone and there is a lineup customers give an encouraging word when they get to the till. Really I am not worried if I can handle the customers, I just hope that they aren't in a hurry and leave.
One guy in a really good mood was trying to ease the stress of the me serving a long line. I asked if he wanted the sandwich toasted and he said " No, frozen," which got the people in line and I to laugh and relax a bit.