Why bother for landfills?

If the landfill can generate electricity that would otherwise be generated, it will convert the CH4 more efficiently than a bus and you don't expand energy upgrading it.

You can power the bus with the already high quality CH4 you extracted from the ground that you would have otherwise burned in to generate the electricity.

Buses have different power requirements than cars; they need a lot more range because they run throughout the day.

I was reading somewhere that in buses in cold climates, heating is actually what eats up all the energy in an electric bus. ICE buses just use the waste heat from a combustion engine.

This scheme is used in real life in Czech Republic