I'm not seeing conspiracy here, just frustration at the amount of trash left around and the desire to do _something_ obvious & easy to at least reduce the problem a bit. "Stop selling disposable plastic bottles" is the first easy obvious step.
So be a capitalist and offer the NPS your solution: you'll operate the $0.50 refund plan, and give them a fair cut of the profits.
I see typical liberal idiocy about sustainability here - from the article:
“A lot of careful thought went into this plan and its implementation,” said Director Jarvis. “I applaud Grand Canyon National Park for its efforts to reduce waste and the environmental impacts created by individually packaged water. This is another example of The National Park Service’s commitment to being an exemplar of the ways we can all reduce our imprint on the land as we embrace sustainable practices that will protect the parks for generations to come.”