Some pros and cons come to mind with the collection bin system. It would make "pack out" truly voluntary. It would get bags off the trail. If someone does leave a bag around, it would be easier to deal with.

On the down side, the weight and volume of bags would be about twice as much as the waste from a toilet system. The bins would require helicopter removal. Or bags could be loaded by hand onto llamas. Helicopters should be a last resort due to the safety risk, noise, and cost.

There was an entire show about "Dirty Jobs" that people do behind the scenes of our civilization, hosted by Mike Rowe. One of those jobs was plucking down feathers, so should we not use down sleeping bags? Some sanitary worker out there would be fine with a job hiking with llamas up the Whitney trail every week to clean out toilets or haul out bags. There should be no need to have Rangers involved.

The toilets at LYV are composting toilets. They might be old, but they were working fine every time I've been there. No noticeable smell during normal operation, but it's still a "Dirty Job" to deal with the waste, which is hauled out on mule trains.