The track fire announcement is an attempt to show idiots the direct damage their own perfidy has to their schedules. Not sure if it works. No asswipe ever hears an announcement over the PA, then slaps his forehead and yells, "I've been such a foooool!!" He's got earbuds in, anyhow.
It's not who you might think, either. I always pictured the litterbug as being a Louie De Palma type, only bigger and fatter, but some of the most nicely dressed people just throw garbage around without a thought. A few weeks ago I'm at a bus stop in outer suburbia and a woman executive type yakking away with a young man chucked a banana peel into a bush. Didn't miss a beat. "Blah blah blah" Fling! "blah blah blah..." Yes, it's natural and it's biodegradable, but it's still garbage and it feeds vermin.
There are firefighters who work for the MTA specifically to combat these trash fires. Can you imagine charging into a burning garbage tunnel? I hope it doesn't involve that.
I couldn't do that job. Christian though I am, I think after the fiftieth time I had to put out a smoking pile of litterbug droppings, I would look at the people on the platform and think, Let 'em fry.