It's a result of cultural imperialism and basic psychology.
Many Europeans are bathed in US media. They see the huge cars constantly on US footage, and some are inclined to purchase these even if they are impractical in EU towns and cities. As these behemoths are introduced in the traffic mix, others in classic smaller cars feel threathened, and their next purchase will be a big tanky SUV to feel less vulnerable.
While SUVs are on the rise in Europe, there's still a large gap between what Europeans consider a large SUV and what Americans consider a large SUV. I'm European and I drive what I consider to be a large car: A 2014 Nissan Qashqai. I'm sure it is considered a small can by Americans. There are bigger SUVs on European roads (like the Volvo XC90) but the true American behemoths are rare here. It's usually Americanophiles driving tricked out RAMs.
Many Europeans are bathed in US media. They see the huge cars constantly on US footage, and some are inclined to purchase these even if they are impractical in EU towns and cities. As these behemoths are introduced in the traffic mix, others in classic smaller cars feel threathened, and their next purchase will be a big tanky SUV to feel less vulnerable.
It self-reinforces from there.