Why in a carseat?

Helen
I am not from the states, and Wonder why so many keep a newborn in carseats the first few months. Where I live, its not recommended to have newborn in a so upright position for longer streches of time. 
We keep them flat in a bassinet, occacionally in a almost flat swing or chair, and then switch to the seat on our stroller at 6-7 months. In the US I have seen tiny babies in the same seats with their head hanging to the side. This annoys me a bit, can't you see its not good for them?