Shopping for food, clothing, hardware, and other items requires interacting with others. Even if they don’t have great manners, you should.
Obey the Right of Way
Grocery store aisles aren’t unlike streets in that it’s important to flow with other traffic, either going in the same direction or the opposite way. You may need to load up on ramen, but don’t block the aisle while doing so. If you’ve stopped to consider which cereal to buy, allow other shoppers to reach around you to get what they need and move on. If a shopper ahead of you is moving at a glacial speed, politely ask them to let you pass….