The fact that plastic one time use bags from the grocery store still exist disappoints me. I'm excited to see some cities banning them - I can't wait for them to be gone for good!
My grandma was using reusable bags her entire life. I can remember as a little girl I would carry in the bags at the grocery store with her. I always thought it was weird, but wow - she was ahead of her time!
At this point in time, with all the research that is done there is absolutely no excuse to not use them. None. If you forget them walk back to the car and get the bags. I will be the first to tell you that when you force yourself to make the walk back out to the parking lot to get those bags you will never forget them again. :)
(And - when you get the hang of that you can start bringing containers to fill up from the bulk section! Baby steps!)