Try carrying more than 2 paper bags full of groceries on a walk of more than a few feet. What will happen is people will buy boxes of plastic bags - for groceries, kitty litter, dog crap - and we're right back where we started.
I refuse to use reusable bags because they're disgusting. The bag fee in St.Catharines magically disappeared after a few months.
"Do you need bags?"
"Here you go!"