Grapes are commonly peeled in Japan, and people will look at you strangely if you eat them skin on. However, Japanese grapes are huge and have a thick, astringent skin that peels off easily.
Likewise, when Japanese people go overseas and start peeling grapes, people look at them strangely. Eventually they figure out that Western grapes are small, hard to peel and the skins are thin and nearly tasteless, so they adopt our barbarian habits too.
Updated to add: Japanese grapes like Kyoho are actually hybrid cultivars of Western grapes (Vitis vinifera) and Concord grapes (Vitis labrusca), which is why they're so different.
Likewise, when Japanese people go overseas and start peeling grapes, people look at them strangely. Eventually they figure out that Western grapes are small, hard to peel and the skins are thin and nearly tasteless, so they adopt our barbarian habits too.
Updated to add: Japanese grapes like Kyoho are actually hybrid cultivars of Western grapes (Vitis vinifera) and Concord grapes (Vitis labrusca), which is why they're so different.