So North America...our roads are typically straighter, many cities and communities are specifically built around automobiles and gradients are much more strictly managed (one of the reason most long haul truck sit around 500 hp, more power simply isn't needed for the majority of our loads).

Now you do see tandems in use here in the US but they are 28.5 feet long each. Canada allows what are called B-trains where they haul tandem 53 footers. Australia on the other hand has what are called road trains...which can be three to five full length vans.