Technically, good and usable Wi-Fi on the trains makes sense - instead of having hundreds of phones all transmitting and interfering with each other, you have a

Technically, good and usable Wi-Fi on the trains makes sense - instead of having hundreds of phones all transmitting and interfering with each other, you have a handful of modems on either side of the train (with external antennas) providing the backhaul for the on-board Wi-Fi. It should even be a win for the mobile providers too as it uses the spectrum more efficiently since less is wasted on interference.