For many Californians, buying "compostable" liners seems like an easy way to keep kitchen scraps tidy while also doing something good for the planet. In Oakland, however, those bags end up in the trash, meaning shoppers may be paying extra for specialty liners their city does not want. Here's what to know SFGate reported that the city's compost program no longer accepts green compostable bags, even if they carry BPI certification. Instead, resid…