The same people that walk home with handfuls of (full) bags.
I must admit, I am guilty. I often walk to the shop and carry the shopping home. but never ever have I had the thought before I go out to take some bags with me. It's one of those things you've just got to get used to.
Not that I'm that bothered, I have a cupboard full of shopping bags, and yes they keep me in bin liners.
They will gradually be phased out, we'll have to get used to it and that's that.