First, cows don’t ‘scrape’ against the barb wire. They might lean against it (to reach over the fence and graze on the other side), but that only leaves small pinpricks from the barbs, and usually doesn’t even penetrate the skin. Their skin is pretty tough, after all.
Secondly, any small cuts from barbed wire fences are unlikely to leave a scar. Especially on a modern dairy farm, where the injury would be seen when the cow is milked that night, and promptly treated with wound ointment and antibiotics. Dairy cows are valuable animals, and very well taken care of by their owners. A painful cut like that would reduce the cows milk production if left untreated. And farmers who allow that to happen to their dairy cows don’t stay in business long!
Third, barbed wire isn’t even used that much on dairy farms. Dairy cows are not turned out into big pastures, only smaller ones, since they have to come in for milking twice a day. Barbed wire has an economic advantage only on vast tracts of land, such as the huge ranches used out west for beef cattle.
Perhaps it’s beef cattle you’re think of. They do run in large ranges with barbed wire fences, are left out for weeks at a time without being seen individually by the rancher, and could have untreated wounds that produce scars. And most leather does come from beef cattle, not dairy cows. Dairy cows are kept and milked for many years; beef cattle go to the slaughter house comparitively young.
I think the two biggest reasons italian leather is more expensive is that:
- Italy has much less land available for large cattle ranches, and
- Italy can get away with charging a higher price for fashions.