Much of America is hotter than Europe. When its 112F outside, ice is required. If you don't use ice, your drink will very quickly become hot. The ice will keep your drink cool for a couple of hours.

NOTE: Do not put ice in beer. This is why the koozie was invented. Also, it's weird to put ice in milk. Just get a milkshake or ice cream instead. Or drink water. It's 112F.