I think in the UK and Japan the model S and model X are far too large to ever be big sellers. There are even some bridges in the UK that the model X can’t cross because it is too wide.
I've driven some really rural narrow roads in my Range Rover and have never encountered a bridge or road I can't use... would be keen to read a source on that bridges thing as it's completely new to me and is failing my sniff test.
However if you stand at the Albert Bridge (which is the one you meant with that width restrictions) you'll see tonnes of LR and RR going through which are wider than that as well as Sprinter vans which are about the same as the X... I can only assume the police take the view that if you fit through the width restriction (which must have some leeway on them as bigger LRs are about 81") they won't bother you...?