Diet, climate, veterinary differences. Going back to bicycles, Brooks of England only use leather from Italy as they discovered that modern veterinary practice

Diet, climate, veterinary differences. Going back to bicycles, Brooks of England only use leather from Italy as they discovered that modern veterinary practices were focusing so heavily on meat production for the animals that the animals were producing a thinner and more brittle leather that didn't age well and had more imperfections. Brooks saddles require a thick leather, single piece with virtually no defects. So they had to find a source of leather where the primary use of the animal was the hide and food and other products were secondary. Fascinating stuff. Beyond particular breeds of livestock, it's about their environment, the country laws relating to veterinary practises and handling, etc.