Convertable Infant/Child Car Seats vs Infant Car Seat (CANADA)

[TRINITY25_99]

I registered for a Graco My Ride 65 Convertable Car seat for our little one when she arrives in June and it holds a infant from 5lbs to 40 lbs Rear Facing, and a 40lbs - 70lbs child Forward Facing. My question is for any Canadian ladies preferably in Ontario, do the hospitals allow you to walk out with baby in arms and put into one of these seats already installed in the car? I've heard that the hospitals will not allow you to do this, they want you to bring one of those Infant Car Seats that you carry with you, and put baby in, and leave that way. I don't see what the big deal is, as long as my baby is properly secured in the car seat before we drive away, what does it matter if the car seat is installed in the car already and not a carry around. Has anyone else had an issue leaving the hospital because of this?