Well not that standard settings are probably just as safe for people far off the height norm, but pediatric recommendations are also a developmental thing. For example with the rearfacing recommendations, a child might hit the weight limit fairly young, but a large 6 month old and small 14 month old probably do not have similar neck muscular development, for instance (just throwing out random numbers). So yeah, it's always hard if a kid is bigger than the norm too, they may outgrow the carseats rearfacing limit or the harness before it is developmentally ideal to forward face, or sit in a booster and keep their head up and the belt positioned safely, even if they are "big" enough.
Car seat recommendations have changed a lot. Driving here feels like a feat of monumental proportions, especially around rush hour, so if I had a kid I'd be doing my best to keep them rearfacing, harnessed, boostered, what have you for as long as possible in terms of the seat limits and their ability to tolerate it. When a baby rearfacing probably was barely done at all...by the time my younger sister was born 3-4 years later, it was done for younger infants, but frequently still people placed car seats in the front seat (no air bags, though). Until I was probably around 6 or 7, we could sit in the front seat as kids, but then all this information came out about the severity of air bags and it was back to the backseat until we were teens. In fact I was probably spared grave injury in the one crash I was in, since I was sitting in the back (driver's side) rather than the passenger side, which was hit with enough force to total the car and completely cave in that side. Although, that was largely dumb luck.
For the record I am only 4'10"
