I agree with your point. I saw a comment above they "solved?" this in some Scandenvian country by mandating the bags cost a ~$1 each. Not sure if that's high enough but I guess the point would be if you make the cost high enough people will quickly learn to bring their own bags.

I admit I am terrible at it. If I ride my bike then I bring something the carry the stuff home but if I take my car, even though I put bags in my trunk, it never even crosses my mind to use them :( Maybe posting this comment will help me remember next time.

On the other hand, my apartment complex demands we put our trash in plastic bags so I use the bags I get at the store for that ... sigh ...