I have forgotten to mention yet another difference between Yosemite Bears and Alaskan Bears.
Apparently the Yosemite Bears are smarter than an average bear. In Alaska campgrounds and trailheads it is common, and encouraged, that you lock your food in your car. I sceptically talked to several different people and campground hosts to determine that apparently these Bears have not yet learned the skill of opening up a car like a tin can.
However, fishermen are required to NOT leave their backpacks on the riverbanks while wading/fishing in the middle of the river. These bears have learned to steal backpacks---probably often filled with the fishermen's catch.