The checkout clerks (girls mostly) at my grocery store have a strange habit of not acknowledging the next customer until the current one has paid. So there’s often a point where the current customer has passed the cash register to put their groceries in a cart, and they’re just waiting for their credit card to go through.
I end up standing right in front of the clerk, who won’t say anything, even though you know they see you out of their peripheral vision. They only say hello as soon as the previous customer has been rung through. Like they’re computers who can’t handle more than one task per person at a time.
It’s quite awkward.