One problem with rear facing seats and large children is that it requires a LOT of space in the car, if you want to fit more people in it. A rear facing seat for a 3yo behind the front passenger seat will make the front passenger space tiny in all but the largest cars.
If you look around europe you'll find that countries that traditionally use small cars (France, Italy, Britain) probably don't use rear facing seats as much. What part of this is cause and what is effect I don't know, but you won't find many families with small children driving compact cars in Sweden like you do in say the UK or Italy. I saw someone in the UK describe a golf as a "family hatchback" at one point. That person hadn't been in the front passenger seat of a Golf with a rear facing child seat behind (The front seat is then nearly touching the glove compartment).