Interesting videos, thanks for posting.
A buddy at work had forwarded me a similar UV thing designed for airplanes a week or two before we started the shutdowns here in the US.
I have no idea the cost of it vs. the items the MTA is using, but one would think a similar thing could be used for a subway car. Does need a person to walk the length of each car with it.
https://www.germfalcon.com/germfalcon-for-airplanes
-Dave