Most of the cities in that list don't have to deal with the things Pittsburgh does.

Singapore is flat, mostly built up after cars were around and is close to the equator and so it doesn't have the freeze/thaw cycle.

Denver, while high up, is dry and with the exception of the western outskirts mostly flat and able to be gridded pretty cleanly.

Barcelona is ancient and not made for cars, but has a very temperate climate and so it also doesn't have that freeze/thaw thing going on.

Warsaw's flat. Melbourne's kinda flat.

Oslo - well you have me there.