For me, this symbolizes what is a much larger overall problem at the parks...
There seems to be a growing issue with guests feeling like they should be able to do whatever they want, be it leaving trash around, not obeying to safety instructions (like staying back behind the lines for the trams, etc.), and just having no sense of courtesy in general towards the CMs or even to other guests.
All of this leads to over-stressed and less-respected CMs, who get more and more frustrated by having to deal with guests who feel like they have a right to do whatever they want. In turn, the CMs end up being less-friendly and almost have to be militaristic in their attitudes before people actually listen to instructions. If I were a CM I'd be totally annoyed by this scene on the monorail because it shouldn't have happened, but I'd also be sure to clean it up.
It all makes for an atmosphere that is less magical than it should be, and is something that COULD be helped if people just acted with a little more couth.
I'm not saying things like this happen all of the time, but there is no worse way to start what is supposed to be a magical day at the parks than having to hear the parking lot tram CMs repeat and repeat to the point of having to yell to get people to stay behind the lines before the tram can move...it's exasperating! Things like this monorail scene will continue to get worse as long as people have less and less respect for themselves and for others when in public and in the parks.
I'd like to think this photo is an isolated incident, but from plenty of personal experience in the parks I can say that it is unfortunately not.