for 1, i was talking about freight trains, not passenger or mass transits or monorails. just freights. and, its not a rail workers job to chase a tagger, so they are making that decision, just like it was the many graffiti artist's choice to run down the tracks, and end up soldered to the rail.
i dont think painting over old art is ever good. it probably started with a few bad eggs messing up the original stuff and eventually they all go over each other.
eh who cares, i think it is art. just

again tho, i dont think there is anything wrong with paiting freight trains. if someone happens to mis step and get hit or fall then that is a mistake that happens. part of the risk i guess.

Couple of comments - and for the record I'm a pretty conventionally trained artist, so my defense of graffitti isn't based in any personal gain - people aren't getting hurt doing graffitti any more than they are getting hurt doing all the other dangerous things we humans do - both legal and illegal. There will always be some who take responsible danger into the area of irresponsible danger. If you have just as much contempt for the woman who puts the bacon grease on too high as you do for this, I guess I can't argue hypocricy but I suspect you don't. You'll probably counter that this is different because it is illegal, however, this isn't the first time in history that artists have pushed the boundaries of the acceptable and even the legal. Some would argue that this is precisely the artist's job - and that the true art is in just such a questioning of culturally accepted morals. Graffitti questions property rights vs. public space. The dynamic of it is in the thrill of creating on the fly and the questioning of arbitrary authority. The imagery is secondary to the conceptual here. And there's a historical connection between artists and tricksters, rebels, and societal outcasts. Art is amoral. And the Dada movement's proponents wouldn't have made such a clear division as you have here concerning the unacceptability of covering over previous work.
But beyond all this - you can't asign blame for one individual's actions onto a whole group of people engaging in the same basic action - not all graffitti artists are killed and have to be scraped off a vehicle. Not all graffitti artists assault when they are apprehended or pursued. Not all graffitti artists do any more damage than their tagging. I'd venture a guess that the majority don't fit that profile at all. Is it illegal? Yep - so is sodomy but that doesn't stop people from doing it. Is it art? Well - I think it can be - and that art and legality are not mutually exclusive.