Reading this post on Serious Eats about the different ways in which municipalities in the U.S. are trying to reduce shopping bag usage, I couldn't help comparing it to the way Switzerland copes with the issue. Here there is no banning of plastic bags or anything aggressive like that. Instead, shoppers are given two choices of disposable containers for their groceries at the checkout counter: free but really flimsy and small plastic bags, which are barely big enough to hold a packet of sandwiches and a drink; or a sturdy paper bag - that costs 30 Rappen each, which is about 25 US cents. I think this is a really smart solution, because having to pay even that small amount for a shopping bag really discourages people from using them. (The supermarket shopping bags are so attractive it seems to Japanese people that they are even sold for more than 10 times what they cost as accessories!)
In Zürich, everyone carries cloth shopping bags, backpacks, and so on to do their shopping as a matter of course, and people with just a little to buy will stuff their purchases wherever they can - I've seen elegant women with vegetables peeking out of their expensive handbags, and businessmen putting groceries into their briefcases. That may be the key really: who says that we need to put groceries, most of which are packed in various forms of plastic anyway, into separate, special bags? (Granted, I would have never thought of this when I lived in the U.S.)
They do things similarly in France too, though there they have plastic disposable bags instead of paper ones. French supermarkets also carry canvas bags, which aren't that widely seen in Switzerland, as well as sturdy plastic bags of Ikea bag quality.