I've got a bit of a people-claustrophobia problem: I don't like crowds milling about me. I'm also an impatient person, and I'm always arguing internally over whether I'm being too pushy in lines and such, because my desire not to be rude is rubbing up against my discomfort in a crowded situation. So I notice things like how people move around me.
People in Walmart sometimes block access to things with their carts, but I think this is because there is no agreed-upon traffic pattern in a store for shopping carts. (I always "drive on the right," or try to, but many do not.) People in Marsh (local chain grocery store) tend to be a bit more polite with their carts and their picking over the produce. They are aware of who is around them and who is waiting to get at the shelves they're standing in front of. People in Sahara Mart (local gourmet/organic store) are very polite.
But people in Bloomingfoods (local organic/co-op store) barge in front of you, drive their carts like Sunday drivers and do other things that make me a nervous wreck. Why is this so? It could be because the aisles are narrower -- and they are. I guess cramming things in a bit closer is a way to maximize income per square foot. It could also be because there's a lot of self-service stuff like bulk grains and fruits (though the self-service stuff at Saraha Mart is even more extensive, and you don't get this behavior). Or it could be that hippies (or whatever they're calling themselves these days, but I recognize the uniform) are just cheerfully unconcerned with anybody else around them.
You'd think that people who are probably conversant with Zen concepts would know where their bodies are in relation to the universe around them. Which would mean that they're not clueless, but that they're following a different set of social norms. Which I find just a tad rude. In any case, after shopping there I know I have to sit down in a quiet space for half an hour or so.