Though it brings a whole host of other challenges, if I could scan my groceries as I put them in the cart, I could bag them in my own containers as I go. I know a few chains allow scanning while shopping but it's not widespread and I'm not sure if they actually allow you to use your own bags. Theft would be a real problem that can't just be hand waved away but it sure would be ideal and do away with most of the grocery bag problem, at least for me.