There's a lot of factors why this technology has a very slow uptake:
1. Cost - How much to implement;
2. Fees and Charges - If it's for customer use, how much?
3. Coverage
The main issue is the "uplink". You could get away with LTE as long as there's more-than-adequate coverage where the bus/train goes to. Some cities use the railway station as a wi-fi hotspot (like London) but once you leave the station it goes. It makes sense anyway because of the roaming issue by some clients.
Unless your city's LTE is poor, you wouldn't want to put wifi in trains and bus because a majority of the commuters would probably their phone/tablet "quota" to do surfing.
