It annoys me when all I buy is a sandwich and the checkout people put it in a bag straight away.
I mean, I managed to pick it up, carry it to the queue, wait for 10mins holding it, and then put it on the desk. You'd probably think I could manage taking it outside to eat it?
Bit more to add...
If people start using their own bags instead of the plastic ones, then there'd be a lot of plastic ones left over. Which'd soon stop them being made, as there's still loads in shops, etc?
Mum uses her own bags, because they're bigger and a bit stronger... and she gets more clubcard points.