If a retail store had everything locked behind glass windows and you had to ask a worker to unlock it so you could get things like peanut butter, I feel like people would buy less things. But when we shop online, the steps to buying stuff is technically worse, because you still have to ask a worker to get an item to you, only now you have to pay before they get the item out, and you have to wait a week or so to be handed the item. The reason people prefer the second option to the first option, in my mind, is that we don't want to directly interact with another person we don't really know.

Extroverts might want to have a whole conversation, which the employee doesn't want to participate in, and even if they did they'd get in trouble for suboptimal work or something. Introverts would rather not interact at all, and will actively try not to look like they're looking at anything just to avoid having a worker walk up to them and asking what they want.

Shops generally don't have all their wares behind glass, but they do expect their workers to interact with customers in the hopes it will lead to a purchase. I think the idea is that if a customer isn't at the cash register then they are a drain on profits somehow just by being there, so everything is geared towards getting them in and through the entire store and then out again as quickly as possible. But they also want enough customers wandering around that the store doesn't feel abandoned, because that leads to the sense that you don't belong there since everything else is designed to lead you to the exit fast.

I think that's why I'm more okay with a vending machine than a shop with glass security and workers following you, both lock their wares away, but you can stare at the contents of a vending machine uninterrupted all day if you really wanted to.