Are you sure there is absolutely no shortage of workers and thus few dozens of people will be completely unable to live their lives anymore after you automate metro? I don't think that is true.
You said that there was "so much more to do for these people" that doesn't "waste human potential" if only we didn't "force" them to do dreary metro jobs. I'm saying that if you take away their dreary metro jobs, most of them will just wind up in dreary non-metro jobs unless we have a better situation standing by ready to receive them, which we don't.
If you want to free people from a life of drudgery, you need to offer an alternative, not just lay off all the drudges.
Edit: Or are you specifically opposed to underground jobs, not bad jobs in general?
The point is elsewhere, it doesn't matter whether the job is bad in my opinion or not. A metro rides on tracks in empty tunnels, and automated metros are technology from 1990's, not using it definitely wastes human potential. On the other hand, tram, bus or car driving is still a hard problem because of the unpredictability, so obviously, even though you're maybe not using your human potential to the fullest as a driver on the ground, it's at least something that a computer can't do, making it a valuable addition to the society, and it also saves these people from being locked to tunnels. I'm not sure about NYC in particular, but there are not enough bus drivers in the whole EU.
