Etiquette is for every person in every time and every place, not just weddings or other dress-up occasions. That includes the supermarket, and it may be that some people need a little refresher about what is Perfectly Proper.
The most important rule for supermarket shopping is to stay out of the way. Be aware of where you are in relation to other people, especially on narrow aisles with extra-wide carts. Accidentally blocking the aisle makes shopping frustrating for others.
In the same vein, don’t take too long to choose. While you dawdle over which kind of mustard you want, another shopper knows exactly which jar of capers to get on the shelf below — that you’re blocking. Give way with a smile if someone asks you to move briefly.
If you’re very tall, expect to help others reach that item on the top shelf. If you’re not that tall, ask for help nicely starting with “Excuse me, please . . .” so that Tall Person knows you’re speaking to them. “I need that” just conveys that you’re bossy.
Count your items before you get to the express lane so that you know you don’t have too many. Some snarky shopper behind you in line might make a point of pointing that out.
Don’t be that snarky shopper. Sorry you’re having a bad day, but you will only end up looking like a jerk.
Never abandon your cart in line to go back for something you forgot. It’s rude.
When approaching the register, get off the phone. The cashier deserves your undivided attention, especially if there are questions about your items. And speaking of which . . .
. . . Know your coupons. Coupon shopping is great as long as you actually buy things covered by the coupons. Not knowing what you’re doing complicates things for the cashier, and frustrates everyone behind you in line.
Smile and thank the cashier and the bagger. They’re people, not drudges.
Always return your cart to the proper place, especially in a parking lot, where errant carts are a true safety hazard. This is such a small thing to do, and so many just cannot be bothered. Don’t be that person.