I applaud the legislators in Melbourne Australia who have just brought in a law requiring shoppers to pay 10 cents per plastic bag at points of sale. I am not sure whether this step will work in their economy. I have heard of similar efforts that were short lived. In a competitive environment, retailers may start eating the cost in an effort to gain customers from the competition. Eventually nobody is charging for bags.
I like the idea of cashiers always asking if you brought you own bag. My local grocer gave me a tall reusable bag with wheels on the bottom last year. It is just the right size for 2 days worth of food for a family of four. The wheels come in handy when I am getting a watermelon.