Maybe this is me getting old and grumpy, but I feel like tourist behavior has also been getting markedly worse, too. I lived near Yellowstone Park as a kid, and while tourists historically have always done dumb shit there, every time I've gone back to visit in the past maybe 5-to-10-ish years it's been painful to see how generally destructive and rude many of the tourists are.
I know this will make me sound racist, and I genuinely don't intend that, but I think part of it has been the huge influx of tourists from China. It's awesome that China's middle class has been growing and allowing more people to travel, but a lot of the necessary traits a person has to adopt to live in a place that crowded and competitive lead to really appalling behavior in other settings. I've traveled a lot and seen people from all backgrounds and nationalities act like jackasses when they're on vacation, but I'd say probably 50% or more of the really egregious jackassery I've witnessed has been from tour groups from China. I know that's rich coming from someone from America, also a major offender in that area, but it's still something I keep noticing :/