A mixed bag

GOD BLESS those San Franciscans. They’re out to change the world, one grocery bag at a time.

Even liberal-leaning Angelenos should be able to find some bemusement in the lefty/greenie crusades of our neighbors to the north, who have legalized same-sex marriage (a great idea, but not really workable at the city level), banned handguns (ditto), forbidden smoking in outdoor parks and made it illegal to discriminate against the overweight or the height-challenged. Their latest target: plastic grocery bags, which were declared saccus non grata Tuesday by the Board of Supervisors.

Instead of conventional plastic, big supermarket chains will have to use biodegradable bags, which can be made of such materials as potato starch. Plastic bags clog our landfills and take generations to break down, so phasing them out makes some sense. But what nettles are the silly claims by San Francisco politicians that consumers won’t pay a price.

Conventional plastic bags cost about a penny each to make. Biodegradable ones cost from 4 to 8 cents. When asked whether stores might pass those extra costs on to consumers, San Francisco Supervisor Ross Mirkarimi, who engineered the bag ban, said that would be “mean-spirited.” Well, no; it would be business as usual. When government imposes extra costs on business, business naturally passes them on to customers.

Unfortunately, San Francisco isn’t the only place where politicians like to pretend that business alone will foot the bill for their environmental initiatives. Any effort to reduce carbon emissions -- from a cap-and-trade system to a carbon tax -- will cost consumers money, in part because financial (dis)incentives are the most effective way to get people to change their behavior.

That doesn’t mean government shouldn’t be seeking solutions to global warming or overflowing landfills. But politicians should stop acting as if there are painless ways to produce results. Principles ain’t cheap -- even ones that can fit into a plastic grocery bag.