From personal experience, when the expectation is that you pack it in, and pack it out. You bring less, waste less, and more consciously collect your litter. For likely a number of reasons not explored in depth in the article, it reduced the amount of trash laying around on trails. Not sure people are purposely throwing trash on the ground. It's more likely people are bringing less and taking better care to store away their trash instead of leaving it loose in a pocket to fall out later. Not having to maintain bins in nature areas is a big win for many conservation reasons. This move is a general win the eyes of conservation (reduce and reuse).
The article also didn't go into detail about the specific bathroom changes. They may have changed to a different type of toilet. Again, conservation being the goal. Spending more money is a solution, but better efficiency is likely a better one.