Well , my post tries to make it pretty clear that it's the very tenseness that is scarey, not the fact that they are New Yorkers. You codl get similar pictures in London, I'm sure - though our tube turnstiles aren't quite so much like execution machines.

My initial assumption on seeing these was that "getting caught off-guard by an unknown photographer when I was hurrying to get somewhere, too" might explain the looks.

But the photographer swears he made a point of trying to avoid that: At the moment that the subjects passed through the turnstile, unknown to them, I took their picture stationed at a distance of eleven feet. I stood there turning pages of a magazine observing subjects out of the corner of my eye, waiting for only the moment when they pushed the turnstile bar to release the shutter. (From this explanatory page.)

The lad with the headphones does look mellow, I agree. But that just brings out how maybe that's the only way to survive in the modern city, - as Timothy Leary put it in a slightly different context "drop out, turn on, tune in".