When it had a plastic bag ban in place, the town of Laredo, TX saved something like a quarter or half million dollars a year on waterway cleanup because there were so many less plastic bags blocking everything.

Then the legislature and maybe state Supreme Court struck down the bans.

No it's not hard, but I still very rarely see people supplying their own bags. Instead they're paying five to ten cents per bag which used to be free but now is a vector for profits to the company, and which used to be made of thin flimsy plastic but is now thick plastic that will take much much longer to degrade. Like I said these bans have been great for the grocery stores profits. It's nice that they do quantifiably reduce plastic waste, though.