That link also states a "higher carbon footprint" for the reusable bags if not reused. I believe the core argument for banning disposable bags, straws, etc is because these throwaway items end up on the sides of highways or in rivers and beaches. If ALL of your trash ends up in a landfill instead of out in the environment, the higher carbon footprint to manufacture them is worth it.
in my opinion the second biggest problem with regulation is that often regulators don't properly account for human nature and some percentage of people being shitty. the biggest problem with regulation is corruption and money in politics. i think regulation is necessary in lots of cases. not sure that my views are representative of most americans though.
You can purchase bags however, I think they cost $1. For my family the ban worked, we always reuse our bags now. Before it was easy to forget even though we try to always help the environment.
http://kxan.com/2015/06/10/report-austin-bag-ban-had-uninten...