I'd guess there are still a subset of people with very limited data plans, or who don't have plans at all and use tablets or laptops.

If you can offload an amount of those people from asking your staff questions about train times and connections and get them checking online instead, I would guess that could be a cost saving?

I suppose it is also something that helps make the train more appealing than other forms of transport. If I know I can turn up 30 mins early and get some work done (or just browse the web), then that help cement the train as a nicer way to travel compared to a bus, or even a car where you cannot work at all if you are the driver.