What is really behind the friction over plastic grocery bags, it can’t be the plastic?

It seems to never fail that several times a year a story hits the news about a community wanting to ban plastic grocery bags. I got to thinking; it has to be more than the plastic. I buy a set of screwdrivers, it has plastic covering them. I purchase a set of lights for my bike, they are plastic. A Brother bought me a sandwich; it was in a plastic container. So many things have plastic in them, is banning plastic grocery bags really improving conditions in the landfill? I suspect there has to be more behind the flap over plastic grocery bags than just the fact they are plastic.