double whammy of high cost of gas and high annual taxes based on engine displacement.

The great bulk of the cars in Europe are 1-2 liters with a considerable segment under 1 liter for better gas mileage and lower taxes. While it is possible to fit an automatic to such small engines, they take a significant toll in both performance and MPG.

OTOH in the USofA we drive (relatively) long distances, have (relatively) cheap gas, and no tax on engine size. As a consequence American cars expanded into large displacement, slow turning engines - ideal for development of automatics.