"Cities are more efficient, suburbs and rural sprawl are inefficient and bad" depends on: A: the design of the suburb B: the underlying economy they're built in C: cultural factors.

When the US contained major manufacturing, it was efficient to have large suburban sprawl - you could build spread out industrial hubs on the outskirts of town.

When the cities were not safe, it did not matter what you said - people left.

"Efficiency" is not a magic word, it has to apply to a particular resource, and does have to consider all costs. Cities are in fact, more efficient in terms of transit costs (of all types).