The purpose of a bear canister is not to protect your food from the bear, it is to protect the bear from your food. Most land management agencies don't really care that much whether you go hungry after a bear gets your food. What they care about is keeping bears from getting dependent on your food and thus becoming a nuisance. In other words, the regulations are in place to protect bears, not you. They have to shoot problem bears because they can't (currently) shoot problem campers. Viewed in this light, everything makes a sort of sense.