Black bears do break into cars in the Sierras, usually in the national parks where the traffic is at an all time high, giving the bears plenty of time to figure out there's a tasty prize in that treasure chest. Yosemite bears are really fond of minivans.

But it does not happen every single day. Bears do get backpacker's food every single day, however, because the people think they can hide food under a rock, or get away with hanging it, and Yosemite is full of bears who are happy to leap out of a tree on a hanging sack, or have small cubs to teach to climb out and chew the rope.