This post http://chowhound.chow.com/topics/820746 inspired me. Have you ever been to a supermarket in another country? Did they have a quirky way of doing things?
In England, I put my hand basket on the conveyor belt and let it slide to forward to the cashier. I do it all the time here in the US. The cashier yelled at me! She told me to remove the things from the basket and place them on the belt. WTF? Her hand wasn't broken.
In Italy, the cashiers SIT DOWN on the job. And in both countries don't hold your breath waiting for someone to bag your groceries for you. Nope, you have to do it yourself. They have a different concept of customer service.
What else have you encountered?