Not after a big shop but if you go to a stand up till with a few items and ask for a bag, would you expect your bag to be packed for you or at least asked if you would like to have it packed?
Before paying for bags came in I’m sure my bag was always packed for me.
A few times I’ve asked for a bag and one is been added to the pile of shopping without me even noticing, which leads to me shoving the items in so as not to hold up the queue.
Having worked in supermarkets, I would never have dreamed of just adding the bag to the shopping without packing the items. It’s not as though it adds anymore to the task.
Maybe etiquette has changed though.