Hasn't been any fatalities in Yosemite and in one case humans actually scared a mother bear in abandoning her cub, so that subspecies might be a bit more chicken than other groups of black bears. Hence no need for bear spray.
Also the fact that a guest doused one of the park's hotels in bear spray, causing a nighttime evacuation and a HAZMAT incident until they could identify the chemical did not help.
http://www.backpacker.com/bear_spray_yosemite_hotel/blogs/daily_dirt/1247
There's a reason they are called "tourons".
