It looks like the days of disposable plastic shopping bags are numbered, at least in San Jose.
District 3 councilmember Sam Liccardo gave a good explanation why in his latest email newsletter:

We pay for those “free” bags in numerous subtle—but substantial—ways. Since grocery stores spend billions of dollars for single-use bags in the U.S., a share of those costs undoubtedly find their way to consumers in the form of higher food prices. Waste haulers and recyclers in San José suffer repeated breakdowns when the plastic bags become lodged in their digesters, requiring manual removal that forces them to shut down machinery several times a day. As rate payers, we pay for those additional labor costs on the order of hundreds of thousands of dollars each year. In a myriad of ways, we also pay for the litter resulting from the thoughtless disposal of these bags, the most obviously through the cost to taxpayers to dislodge and clean the bags from clogged outfalls, sewers, and streams. In addition to these costs, we face the challenge of reducing the bags that are filling our landfills as we try to move toward “zero waste” strategies to address our lack of landfill space.

…

Plastic bag recycling has several limitations. It’s not easy for consumers to know which kinds of plastic can be recycled, and any food debris or other contaminants will make the plastic undesirable for recyclers. Market realities also make it challenging; as reported in the Christian Science Monitor (March 29, 2007, “Seldom Recycled”), it costs $4,000 to process and recycle one ton of plastic bags, which can then be sold on the commodities market for $32. Where recycling often requires heavy taxpayer subsidies, it’s better to keep the product out of the waste stream rather than spinning our wheels in quixotic recycling efforts.

And not only are the costs of keeping the disposable bags high, the inconvenience of doing away with them is really minimal.

Travelling in Europe last year, I got to see how a bag ban could work in practice. In Hungary, Austria, and the Czech Republic I never saw a grocery store give away a bag, but it was no problem. The key is one thing that doesn’t seem to have caught on here yet: re-usable plastic bags. Much heavier-duty than the current disposable bags, they could still be folded up and kept in your pocket. They cost only about 25 cents each, and lasted through dozens of grocery trips.

There’s still a few hurdles before San Jose truly goes disposable-bag-free, but the city council deserves kudos for setting this in motion.