As the other comment mentions, staffing is a significant cost in many systems, especially those with lower ridership numbers (though presumably if this city nee

As the other comment mentions, staffing is a significant cost in many systems, especially those with lower ridership numbers (though presumably if this city needs such a large bus, it's not really in that category). Of course, as large as this bus is, it's still nowhere near the capacity of many trains. Commuter trains in places like Japan can carry upwards of 3,000 people on a single train (and of course then there's India...). When you really need capacity, the costs of the dedicated infrastructure for trains start to become worth it.