I moved to the US a few months ago and one thing that still confuses me to no end is to how to behave around grocery baggers in the store.
I usually walk to the store and bring my own backpack or tote bag, so I don't need the paper or plastic bags. I feel so weird handing my backpack to the designated grocery bagger, though. Sometimes I have ended up just bagging the groceries myself, but that was awkward too, because then the grocery bagger person had nothing to do.
Edit: I'm in Massachusetts and talking about Market Basket specifically, where there is one bagger for each lane.