OK. When in doubt, read the regulations. After doing that, they're not tremendously obvious: The "can't use a bear box" regulation applies only to the three areas in Sequoia Kings where hanging is prohibited (Dusy Basin, Mather/Rae/Kearsarge/Bubbs/Forester & Rock Creek). And what the reg says is you must have enough canisters to carry all your food & garbage.
I have to admit, it's not a reg I get hugely excited about in the sense that I expect a party on their first night or two to fit everything in their canister. BUT, I would absolutely expect those folks to be at a box when they can't fit all food to be in their canisters AND I'd expect them to have a reasonable number of canisters for their party size. That's just me. Other rangers may be more exacting in their interpretation... .
Through hikers on the PCT or JMT are not actually required to have a canister in those areas but ARE required to camp at a box.
I have to admit that while I understand the logic of a bear not playing with your food at all it's a new one for me, it seems to go against the very idea that you just place your bear barrel on the ground away from your camp, it seems that we shouldn't hold that idea against the Ursack but place it under the same responsibility category as counter balance, your responsible for placing or securing your Ursack in a way that a bear cannot carry it away, after all this is the only thing that holds it back.
I dunno if I'm following you here. Again, it's not the bears "playing" with anything that's the problem, it's that their natural behavior is changed by us not securing our food in a bomb-proof way. The Ursacks have been shown to not be bomb proof. Bears get a "food reward" -- either a tiny taste or enough positive reinforcement to keep trying to get into the sack. So you can use it but, as noted, only to counter balance like a regular stuff sack -- not leave out on the ground because, like a stuff sack, it doesn't work... .
That's not true of canisters. For the most part, bears have given up even trying to get into most of them, though they get tested occasionally. Note the failure of a previous model screw top of the Bear Vault a few years ago. A single bear at Bubbs Creek figured it out forcing that model to be banned there until the company solved the top failure.
but as I understand from talking to various rangers that the primary push for making canisters mandatory in Sequoia and Kings Canyon National Parks is because of pressure from groups concerned with minor violations in the wilderness laws
Well, kinda, sorta... . The objection to the boxes is that they're an aesthetic intrusion in a Wilderness setting. However, the Wilderness Act does allow structures and other intrusions to the extent that it can be shown to preserve wilderness values. I would argue (and I'm not at a management level to do so...) that keeping bears wild directly benefits wilderness values, even at the expense of the intrusion of a box.The boxes do that and I think it can also be shown that if they're taken out, bear/human interactions would increase, especially near trailheads. I don't see box removal as an immediate concern, though maybe someday... .
Whew!
We can quibble forever in a scholarly debate on what is and is not allowed and where. But again! It's all about keeping food away from bears. If a hiker is seen to be gaming the system, then your cheerful public servants are going to give you an earful (in a polite and respectful way, of course).
g.
