I should have mentioned before that he is also sore on hard terrain, rocks, dirt roads etc, I'v ridden him cement before and he seemed to do fine but everything else that's hard and relatiively uneven he get uncomfortable. Mostly on his front feet, never seems to have to much trouble with his back feet.
My TB wears front shoes because otherwise he's gimpy on hard surfaces. He doesn't need them on his back feet.
You shoe or not depending on the horse, not what someone who isn't your farrier tells you.
Mustangs 'do fine' without shoes because one, nobody rides them, and two, those with bad feet die early on in their lives. You can't compare a feral, unridden horse with one who is expected to carry the weight of tack and a rider, and asked to do extreme physically challenging disciplines.