There’s a difference between a ban and just not facilitating the activity. Not selling cheap bottles easily tossed as litter by those not smart enough to at least bring their own may not solve the problem, but it reduces facilitation of it.
They aren’t taking the entire option away from the sight seers, just rearranging the options. Note that you can still purchase a water bottle for $1.99 and refill it as much as needed at the free refill stations.
•Grand Canyon souvenir water bottles cost as little as $1.99 and can be filled over and over again with FREE Grand Canyon spring water. When you refill a reusable water bottle, you save money!