the major reason that there is a difference between our bears ,is that many of your hiker / outdoor backpackers etc carry pistols and we can not even if your bears are not out right killed the learned behaviour that is passed down from mother to cub is still happening there where it is not happening here
I'm sure you are familiar with bears in northern BC but I agree you seem to be generalizing about bears elsewhere, as has been pointed out. There are not many hiker/backpackers in the Sierra carrying pistols, and nobody shoots at bears in hiking areas that I've ever heard of. Yet we have very few bear incidents (I found 12 "bear attacks" listed since 1980, none fatal) other than incidents of their acquiring humans' food. i'd guess that most of our bear population is in national park/forest land where they are protected and their access to our food is (theoretically, at least) limited. It's not that they are learning to fear guns; I'd guess it's a rare bear in California that's had any experience with guns. Banging pans, shouting hikers, yes; guns, no. But there does not seem to be any rationale for arming oneself against bears here with the current bear situation.