Perhaps this depends a lot on location. Parking is a nightmare at my local Costco. The employees are friendly enough most of the time. I truly admire the value and business model but Costco is pretty much the absolute worst shopping experience I can think of.

It's because they are so busy. Yeah, costco is the one store I go to that people seem to have 0 spatial awareness. Every time I go, someone will just stop moving in the middle of the aisle, creating backups, without any shame. But I bet if your other local grocery stores were as busy as costco, they would have the same issues.

Agreed. The entire store is wired to encourage impulse buying and keep you from making rational decisions about whether you'll be able to finish that 3lb container of guacamole before it goes bad.