Although not as extreme as San Francisco and the Manitoba town of Leaf Rapids, both of which have banned plastic shopping bags, the province of Ontario is taking steps to reduce the number of plastic bags used by 50% to help the environment.

Good!!!! NJ ShopRite gives you 2 cents a bag if you reuse them.
My suggestion: supermarkets get most deliveries in boxes, so why not use the boxes to package groceries at the check out line? Then the cardboard could be recycled.

Your suggestion is right on! We have been using the store's delivery boxes to package our groceries for a couple of years, kk. The grocery stores are glad to have the boxes taken away without having to break them down, and we are glad to forego the plastic bags and glad to get the boxes. We reuse the boxes until they are no longer usable and then recycle them. The larger of the two groceries we buy from charges 5 cents per plastic bag, encouraging customers to use the delivery boxes, which they keep near the checkouts.