Most likely, the lady just wasn't paying attention and would have been struck with or without earphones. If the train is really quiet, then, the lack of phones probably would not have helped.
I wear phones when I feel like it, go without them when I feel like it, and I don't think it affects my personal safety at all. I am keenly aware of my sense of hearing and will not damage it by cranking music up loud enough so that I can descend a hill at 35 mph and still hear my music over the rush of the wind. In fact, I have carefully selected a pair of wrap arounds (they fit on your ears like the earpieces on wire-rimmed glasses) just for their aerodynamic design. Each ear piece is a perfect hemisphere and does not catch the wind and cause a lot of wind noise at my ear.
When I wear them, the simply present another set of sounds to my ears. They do not block out the outside. I can hear traffic approaching (not that it helps much), and I can hear horn honks and conversations of passers-by. When I wear them, my goal is to listen to the music while I ride, not to block out the rest of the world.
I vote for being careful when you ride, but, also for following your own desires with regard to the use of headphones.
Caruso