Although here in Japan such devices are rarely necessary (they do have ring-necked bears and brown bears... relative of the grizzly... , wild boars, raccoon dogs, and macaques here), having lived in the US and spent a lot of time in the mountains there this is a very interesting idea. While I read the information about how it works I started thinking about all the methods that animals use to deter potential predators, especially insects, the masters of chemical solutions.
Some other ideas:
3) very bad and tenacious smell
4) display- aural or visual
6) difficulty in dislodging
7) very bad or tenacious taste
8) some kind of non-lethal toxin
1) The first line of defense. If you can't be seen then maybe the predator will go away.
2) If you look like something the predator is scared of or dislikes maybe the predator will leave you alone. Many bee-flies look like bees or wasps, many non-lethal snakes look like poisonous snakes (coral snake and milk snake).
3) Many animals and plants use this approach. Just think of skunks and stink bugs. Very often the smell is very hard to rid of, reminding the predator for a long time afterwards about your unpleasantness.
4) Small animals and plants often use this. By making a very loud, threatening noise or appearing to be bigger than you are you can often scare predators away. Bearded lizards, praying mantises, cats with hair standing on end, cobras with hoods opened, even cockroaches with their sudden movements. Very often animals will employ big eye-like marks. Sometimes the animals or plants grow bigger, by inflating themselves or throwing up large displays. Some frogs and fish, like the blowfish, will balloon to twice their size or more.
5) Porcupines, cacti, spiny toads, scorpion fish, all use spines to keep predators at bay. In the case of porcupines and many caterpillars the spines break off, again reminding the predator of how unpleasant you are.
6) By using the surrounding environment to their advantage, many animals and plants make it difficult for them to be dislodged or moved. Chukwallas with their inflating themselves between rocks and insects that slide into tight spaces are good examples.
7) Many animals and plants, once they've been discovered, resort to tasting really bad so that the next time the predator happens upon them the predator avoids them. And like the bad smelling animals, often the taste is tenacious and even sickening so that the predator spends considerable time trying to rid themself of the taste. Very often bad tasting and bad smelling animals have bright colors (usually yellow and black, or bright red).
8) Toxins are very common among insects and amphibians. Many caterpillars use all kinds of toxins. Some are related to bad taste or bad smell, some are very painful (cayenne is one of the most painful toxins in the natural world), some drug you and make you feel sleepy or delirious.
9) Not many animals use this as it is hard to mix the chemicals, but insects like the bombadier beetle employ a super-heated acid spray through a flexible nozzle that really does its job. I know, because I've been sprayed in the eye by one! I was screaming for about half an hour afterwards!
10) Lots of animals will leave something to tempt the predator away. Sometimes it is a broken off limb or body part, sometimes it is an enticing alternate meal in a different location, sometimes, like with the killdeer it is putting yourself in harm's way and drawing the predator off away from something you want to protect.
11) It never hurts to have a great sense of humor. You make a bully laugh hard enough there's probably little danger of being attacked by one. You could always have a picture of you beating up the bear on the cover of the food bag. I'm sure the bear would get a kick out of that.
These are just a few ideas, There are millions of ideas out there in nature. If you look at the bears' environment and lifestyle in the US, look at how animals and plants have evolved there to deter bears from getting to them. I'm sure there must be a lot of specific examples. If you can't see them, then you are not looking closely enough at the environments that you are walking through. Only humans use bear bags, after all...