When the first European explorers reached the New World, they were astounded to find that the North American Indians had not progressed beyond the Stone Age.
Hundreds of years later American travelers go to Europe and are astounded to find that European cultures have not discovered the shower curtain.
What is it with these Europeans! Why can't I come over here and take a shower without leaving an inch of water standing in the bathroom?! They got a tub, running water and a shower head. It's not a huge leap to make it to a shower curtain!