European conditions and regulations favor a cabover configuration:

1. Shorter length. European countries have stricter overall length regulations.
2. Better overview when in dense traffic.
3. More urbanized and older road network also favors shorter and better overview as you have a better idea where the outer corners of your truck are (good when in tight spaces).

P.S: Meanwhile a conventional truck is more aerodynamic, it's easier to access the engine and it's a smoother ride since you're behind (and not over) the forward axle. So it's a favored configuration when you have longhaulers on long open roads (like much of the US).