There is a big piece of the equation being left out here. The guests today. As someone who is old enough to remember Disney as a kid in the late 60s and beyond, it was MUCH cleaner than today. But so we’re the guests. Then, people dressed nicely, threw trash in containers and cleaned up after themselves. My last few visits to a park, I watched people toss garbage into the bushes, drop it on the ground, leave food, cups and waste on tables and benches, try and take drinks on rides, drop paper wrappers as they walked, etc, etc. There was little of that “back in the days.”
People just seem less concerned with anything but themselves, and walking 10 feet to a trash can as an inconvenience to them. So you get more crap on the grounds, and annoyances to those who care. And IMO, it is only getting worse each year.