The same reason that most of the the Dutch sound American when they speak in English... they grew up watching popular exported American TV shows subtitled in their own language... so they naturally pick it up.
Probably the same reason British chav kids use phrases such as "is you dissin my homie nigga?" when they actually grew up in a nice 4-bed semi in Surbiton where '8-mile' is not an infamous Detroit street, but is actually a local fun-run that Daddy took part in with his civil servant colleagues.