You know puddicat, ive found the complete opposite at work, as you probably know i work on a till at the co-op and its the kids and teens who almost demand a bag, even if it's just for a couple of chocolate bars, and sadly, our policy is, if they ask for a bag they've to get one.
Also, now this may sound racist, but its not, it's a fact- the asian community do not use re-usable bags either, again they'll ask for a bag even for the smallest of items.
The elderly on the other hand have really taken to it, the majority of them keep a good few reusable carriers and cotton shoppers, and get quite crotchety if you offer them a carrierbag!