It's more about pedigree & weight than anything else. Italian bicycle manufacturers were producing and delivering 20 pound steel machines to the US since the 60's. Most Japanese steel bicycles couldn't even come close to matching that weight. Until at least the 80's. Then, if you could even find a lightweight Japanese bike it was still going to weigh around 21 or 22 lbs. The Italians were the champions of lightweight racing design for decades.