Tl;dr: Spirits of dead commuters on trains and subways tune out of their surroundings, just like they did in life. Calling on them for any working might prove to be a frustrating exercise.
Ever ridden a train or subway when it’s not rush hour?
I did yesterday, late at night. It was me and about 4-5 passengers scattered through an otherwise empty car. Of course I found a seat. At some point I meditated to pass the time, and became startled when a guy came close and stood over my personal space. He wasn’t one of the 4-5 other strangers in the car. It took him a few seconds to notice that I was there, and then he seemed as puzzled at my presence as I was of his.
While he was staring at me wordlessly, it became apparent that there were many more of them around him - many. They were standing, crammed to capacity, in the car’s aisles, holding onto the poles. Dead commuters, riding the train to workplaces and homes that they’ll never reach.
They couldn’t or wouldn’t notice me at all. They stayed silent, kept their heads down or stared vacantly in the distance, avoiding eye contact even with each other. They tuned out their surroundings, just like living commuters do during rush hour. I got the sense that these commuters never get off this train - they just ride it round trip, day in and out, tuned out to the reality around them. Even when I got off at my stop, none of them acknowledged or tried to follow me. That one guy stayed where he stood.
If you’re curious, that one guy might have been headed home after his job at UPS, because he was wearing a uniform that was in one shade of brown.