I think you overestimate the extent to which the war ravaged the countryside. Some cities were destroyed. Most (most!) of the rest of Europe, the towns and villages, wasn't.
The U.S. has essentially stopped building urban interstates since the late 70's, when opposition from residents became too strong to ignore. I don't foresee this changing in the near future.
My understanding is that construction costs in Europe are rising as well due to (among other things) increased use of tunnels in urban area due to opposition from residents.