I do my weekly (Weekly? Sometimes I'm there almost daily...) shopping at the same two stores; Trucchi's and Shaw's. Both of these stores usually have baggers at every check out and they obviously train them on how to bag properly, meaning that they put the frozen items all together, bread and eggs in one bag, meat is never in the same bag with anything else, etc. I've never had a problem with the way the groceries are bagged.
I only bag groceries myself if there happens to be no bagger, because normally by the time I've finished loading all of my groceries onto the counter, they are being bagged immediately and put back into my cart, anyway.
I have never seen a store where they want you to bag your own groceries, I don't think there are any around here.