It's not a black and white issue which is why you are failing to understand. It's a spectrum where the higher you are, the better you can see. It's not blind in a saloon, perfect vision in an SUV. The highest driving position gives a better view.Because it makes no sense to me really. I can see fine from a saloon car as can most people. The only decent argument I've seen on this thread for a high driving position is if you very specifically drive on country lanes with hedges of a certain height. Other than that it's a strange argument
If you've ever been to a football match or a stadium, which I assume you have, there is a very big difference between sitting pitch side and sitting in the upper tier. You can see most things low in the stand but your perspective gives you a better perception of depth and positioning the higher you go. It's really not a difficult concept.
It's not just about seeing over hedges, everything is easier to see from a raised seating position. There is a point where it becomes a negative (like HGVs being unable to see what is directly in front of them).
I drive a saloon and an SUV because we have 2 cars. In the SUV when I'm driving behind a smaller car I can see the car in front of that over the top more easily. If they break I can react at the same time as the car immediately in front of me but I don't get that view as well in the saloon.