Mike- you are correct that is where the canyon wall climbing bears video was from.
Paul- the only bear encounters that I know of have been in the mountains and at the roadside campsites where there are either food lockers or hard sided vehicles to store food in and maybe lazier campers have not done a good job.
This has been a slowly escalating issue. Bears were hunted out of the area pre-park and then returned after 40 plus years, coming from Mexico, in the late 1980's. They immediately installed bear proof trash cans etc. to keep the bears from becoming habituated to human food. They are mainly in the mountains above 5000' but do move through the lower foothills between the Chisos and Mexico.
We think that it is total overkill for a handful of bears but then it is a totally different environment from the Sierra and Rockies because in Big Bend both food and water are in short supply. Saguaro has kind of similar requirements but I don't know how long they have had them.
There are also additional/different tensions with LE rangers than in other parks because of all the border issues. Sometimes it seems like the LE rangers and Border Patrol have more say in how the park is run than the traditional park service staff.
I have been going to the park for over 40 years and never had any kind of critter issue with food or anything else but I also appreciate trying to keep the bears un-habituated to human food as it is a fresh start so to speak.
It also seems to be the trend that the immediate NPS or FS knee jerk reaction is bear cans like the recent thread on Maroon Bells and bears.
As Luke says, it is an additional load to an already water heavy pack in the desert and cost/hassle if you also need bear cans to cache water for longer cross country trips.
Sigh.