"Why chase the bears off? Let them learn there is no reward for messing with the (hard to get ahold of) canister."
If you take Yosemite black bears as examples, they are pretty crafty. The experienced bears will walk up to a bear canister, sniff it, and walk by. Once in a while, they will paw it to see if it will accidentally dump its contents, but then they walk by. The inexperienced bears will spend a lot more time trying to figure it out. They can smell food, but they can't get to it. In some cases, they will try to chew on the canister. That really doesn't do you or the bear any good. So, sometimes it is best to give it a minute or two on it to discover that it is tough, and then chase it off. Besides, some bears are really persistent, and they will keep you awake half the night as they try different things. I've found the best method is to shout at them, run directly at them, bark like a wild dog, throw rocks, or all of these.
Yosemite black bears are more like oversized wild dogs. They could hurt you if you were stupid.