[bluGill]

Extept that you have to maintain the roads anyway. taking a few buses off won't save much so long as the road for trucks exists.

[bgnn]

Most European cities are transitioning towards dedicated bus lanes. In that case, in principle, that can be light rail or tram too. The biggest problem is crossing with normal roads. Trams are more tricky to implement than busses.

[dzhiurgis]

Roads for buses and trucks are far more expensive than for cars. Car drivers are absolutely subsidizing bus passengers by order of magnitude. Per passenger mile even Uber is cheaper.

[h2zizzle]

Not when car volume is several orders of magnitude higher than bus volume. Bus passengers are subsidizing car drivers.

[dzhiurgis]

Busses and trucks damage roads up to 30,000 (yes 30k) more than cars. Cars absolutely subsidise all roads.

And btw neither buses nor trucks nor cars have some constitutional right of way.