Yeah, I remembere that story damned near killed me when I first read it.
Yet, at the same time, I'm not surprised in the least. Being perfectly objective, had I walked past him while he was playing, I'm sure I'd have at least looked at him, and I'd probably have slowed down and lingered for a moment or two - even on a lo-fi video you can hear that the guy's tone is something special, and his touch on the instrument is masterful. But, I don't really know that much about violin music, so I wouldn't be able to really discern between a guy who was quite proficient, and a true world class talent.
And, you really can't understand the dehumanizing aspect of public transportation until you've done it. The Boston T isn't bad compared to some, and the Red Line is one of the cleaner/nicer lines, but when I first moved to Boston it took me less than a week to get the hang of recognizing the locals and recognizing the out of town visitors - the locals were the ones wou would never make eye contact.
Part of taking busy public transportation day in and day out, where you're shoved into narrow cars and stand shoulder to shoulder with complete strangers, many of whom are carrying bags and briefcases and a certain amount of jostling and invasion of one's personal space is inevitable, is the ability to "shut out" the rest of the world around you. It's not an invasion of your personal space if someone falls into you or has to stick their arm an inch or two to the left of your face to grab a handhold if you can mentally "shut off" the humanity of the people around them, and think of them not as a living, breathing human being, but as just another inanimate object near you. No one feels "invaded" by being close to a rock, a tree, or a wall. It's the same idea, and if you spend enough time on crowded public transit, you quickly learn how to do it.
It'd take something pretty damned jarring to shake down that wall between yourself and the rest of the world, and unless you're a music lover this probably isn't enough. :/