I sometimes take a peak into European busses but I don't see 25-30 people sitting in there on average. That is a lot of people.

Busses, at least the one where I live in Europe, are very loud, noisy and smelly. I'd rather have 20 cars pass my home than one bus. I don't hear or feel those cars but once that bus passes my coffee cup visibly shakes. I also don't mind cycling behind most cars but cycling behind a bus is a terrible experience. You feel the heat blasting out of the rear-right side and the diesel smoke is terrible.

Europe is made up of a lot of different countries, even in the UK there's a big difference in bus provision depending on where you are.