Big houses and big yards? I've got a bungalow that is smaller than any house I lived in growing up (probably by a factor of two).
Urban sprawl may have a huge cost in infrastructure, but the lack of planning to put in commute alternatives (like trains) are just as damning. In Germany, there are friends that live 30-40min outside of Munich and happily take the train daily. They don't necessarily want to live in the city. Which goes to your argument of "Low-density urban sprawl largely also makes public transport uneconomic" -- in general, sure, but again infrastructure planning can offset this.
This country, unfortunately, doesn't believe in planning for infrastructure. Trains? Unprofitable boondoggles! (or so some think)
Agreed. I live in a flat in semi-central London and I cycle to work in a little more than half an hour. Life is good, but during weekends it really rubs me that I have at least an hours worth of travelling to do before I can get to some uninterrupted countryside.