Do you not usually carry a rucksack or shoulder bag? If you're having to use a new plastic bag every time it seems like it might benefit you to get one - they're much more comfortable to use too.

Where have plastic bags been banned? Everywhere I've seen these policies in place, there has just been a mandatory charge added for receiving a bag. This seems reasonable enough to me even without waste or environmental considerations.

Well not banned, but they added a 15c charge for thicker ones, so now I spend more and waste more plastic than I was previously. The thicker bigger ones and the smaller thinner ones that used to be free got reused as garbage bags nearly 1 to 1.