I've been on the T during rush hour thousands of times, packed in shoulder to shoulder with everyone else trying to get either to work or back home. I think it's a safe assumption that the people standing next to me on any given ride are also accustomed to the conditions.
And yet... and yet yesterday I got the stink-eye from someone I accidentally bumped in the shoulder. Imagine that, riding in a jammed subway car and someone unintentionally makes contact with you? Hell, I'm surprised when it doesn't happen.