I guess rush hour traffic can be viewed as waiting in line. One difference is that you can change lane, although that's one thing that really irritates people. The weavering and the lane cutting. Or how about those people that park their grocery cart sideways in the middle of an aisle? It turns out a book has been published on the subject of grocery store etiquette. No kidding!
New Study, The 'Best' Ways to Incite Road Rage
Queuing psychology: Can waiting in line be fun?
Why do people park their shopping carts right in the middle of the aisle in stores?
A Book of Grocery Store Etiquette: A Guide for the Consumer, Based on Over 30 Years of Observations and Aggravations
I see shopping cart rage in all the time in HEB where people just pull out with their cart in the store oblivious to anyone else walking or right of way. I also don;t like when parents let their little monsters push the cart or people in cell phones pushing their cart and not paying attention.
My casual observation regarding shopping carts in the grocery store. Men generally park the cart to one side or the other. Women - right smack in the middle of the aisle. YMMV.