Dunno what's happening in America with the bag situation, but here in Australia it has become the norm to buy reusable bags from the supermarket.  No one has a problem with anyone bringing in their own bags.....in fact it's pretty much a no-no to use the plastic ones provided in the supermarket.  Any plastic ones that you do use you can return to the supermarket's recycle bin.  Nice green bags with handles even can be purchased for $1 and are nice and sturdy.  Paper bags don't even exist here.  If anyone has a problem with the bags they can feel free to search them, right?