This is simply not true. I've only been out there once (2 weeks in Banff, Jasper, and Yoho), but the vast majority of hikers I saw did NOT have pepper spray.
Maybe I should have made my statements more clear. GNP is different from Jasper, Banff, Yoho, etc. Jasper, Banff, and Yoho are more like the ADK's. There is public property and private property mixed together. So, you do get a lot of people who are traveling thru and stop and get out and hike a little bit. Or, maybe do a day hike. I don't consider those people hikers. I consider people on this forum hikers. So, when I refer to everyone, I refer to serious hikers who hike every day on their trips to these regions, backcountry hikers, rock climbers, etc. I don't consider people who walk up to the base of Kaaterskill Falls in Flip Flops hikers. Or, even someone who hikes once a year. Maybe I should have said Serious Hikers instead. My mistake.
I do belong to a number of hiking forums out in that region. I don't know any hikers on those forums who don't carry bear spray. There are also hikers who keep their bear spray hidden from view. So, if you don't see it, it doesn't mean that they don't have it. Sometimes it is in their jacket pocket, or in a pack pocket, or some other hidden location. I carry bear spray on 100% of my hikes. If you have ever hiked with me, you would be surprised that I have it. It sits inside my pack on almost all my hikes. I only bring it out if I think that there is a pretty good probability of an up-close and personal bear encounter.
I could consult Dave Parker, who runs a number of hiking forums out west. He works for one of the bear spray mfg. He might have a better statistic on this issue.
Grizzly bears are the same whether you are in Yellowstone, GNP, or Jasper. Some have good personalities, and some don't. Each encounter is different. Never know what the encounter will be like. But, you should never use the same procedures with grizzlies like you do with Black Bears. Black bears are almost always very docile, where griz's are quite aggressive. If you ever stay at Many Glacier Hotel inside GNP, you can sit on the porch next to Swiftcurrent Lake and watch the grizzlies and other animals interact on the mountainside. You often see a lot of charges when other animals encounter their feeding envelope. You can learn a lot about them by watching them.
As far as dropping your pack, this is exactly what the Rangers do not want you to do. You can hear Rangers saying this statement often, "A fed bear is a dead bear." Once it is fed, they will kill the bear. Grizzlies learn by experience. Once they learn that humans have food, they will pursue them relentlessly. If you are going to hike where there are grizzlies, you need to learn about how to hike around them. Follow the rules, and you will have few problems. If you do have a bad encounter, bear spray is your insurance policy.
Climbing trees or running often incites the griz to pursue you. You would be amazed how high they can go. Some will go up in the tree until the tree or branch breaks. Or, they will shake the tree to make you fall out. They would have been better off dropping a piece of clothing or a hat. This will sometimes distract the bear long enough for them to get away.
Pepper spray and bear spray have different chemical composition. Depending upon which state you are in, they are treated different legally. If I recall correctly, bear spray is 10x more powerful then pepper spray.
Heard this on NPR late last night...
