To make a screen with any ratios other than 16:9 seems to be very expensive nowadays though. I personally would rather a laptop be cheaper than to have a 16:10 or 3:2 monitor.
Then again, it would probably be only visible in greater margin for the manufacturer :/.
It's probably not that they're much more expensive to make, but there are much better economies of scale with a 16:9 ratio... the same panels work for TVs too
There isn't a market for 13-inch TVs... But mathematics support your reasoning about economies of scale: with constant, 13.3 inch diagonal, higher the aspect ratio, lower the screen area,thus less raw materials used, cheaper to produce.
Then again, it would probably be only visible in greater margin for the manufacturer :/.