Even as a libertarian, I support bag bans and make sure to pack my reusable bags when I go to California and Hawaii. This is an issue where your poor choice affects a lot of others because the vast majority of those 21 million bags a year are not being recycled. When a woman is picking up bags off her property every single day, you have a problem. These bags get carried down stream and eventually wind up in oceans. Animals as small as birds and as large as whales are dying from eating them. Killing a whale because you're too cheap and/or lazy to bring in a 99-cent bag is not acceptable. Besides, Costco doesn't seem to have lost many customers by not having bags.