Anyone who has worked in high-end construction can tell you that they’re very common in rich people’s houses. The reason you don’t see them more often is that most people don’t want to pay for them. Americans tend to value the size of their houses more than anything else, and since McMansion developers know this, windows are one very easy way to cut costs.

They’re also a lot more common in older homes (like mine) because if you’re going to replace all your windows (which you should do for energy reasons), you might as well get the good ones.