Answer to the question in the title, hidden deep inside the article: Length limits. "Maximum length of a truck with a semi-trailer in Europe is 18.75 meters."

Answer to the question in the title, hidden deep inside the article: Length limits. "Maximum length of a truck with a semi-trailer in Europe is 18.75 meters." so length is at a premium that cannot be outweighed by the other benefits of the "classic" US style design. Higher speeds and bigger roads are other reasons to have the US truck in the US but not Europe (among many other advantages of the design) but the stated fact that "European style" trucks were much more common in the US when the US still had length limits indicates that the length limit is the deciding factor.