As far as I know and I could be wrong but Yosemite , kings and sequoia , San gregornio , almost any place where bears exist require bear canisters due to the increase in bear human interaction.
All of Yosemite needs them but in SEKI they are only needed in
these locations.You may not be required to carry a canister but you are still responsible for keeping your food away from animals. There is a difference between not needing one by law and not needing one based on animal populations.
