It is, at least in a place like LA. Fares are like less than 10% the actual total cost of an average bus ride. https://www.reddit.com/r/LAMetro/comments/1orftnt/should_you...
Now if you’re ONLY serving high density and high passenger volume times, buses are incredible.
Is your point that busses aren't profitable? Why do they need to be?
I am sure if you did the math, having the occasional empty bus does not hold a candle to the amount of dead mass being dragged along in single-occupant cars.
The wear-and-tear on the road from the sheer volume of cars alone makes them cost more to us as a society than busses.
So regardless of density and passenger volume, busses are incredible.