New York Times: Three years ago, San Francisco was the first city in the country to ban the ubiquitous plastic shopping bag, but it was quickly followed by Palo Alto and Oakland. These cities, and the Bay Area generally, were at the forefront of the movement to keep single-use, filmy carry-out bags out of landfills, out of the bay and out of the innards of marine mammals. But now cities are reconsidering, in part because of lawsuits filed by opponents, but also because too many shoppers in San …