Yeah, I wonder about that too. Our plan is to get our neighbours interested enough to check their own windows, increasing the sample size. The oldest house on the street was completed less than seven years ago, so they're all roughly the same vintage.

[EDIT] Here is a link from a home inspector in the USA: http://caveatemptorlv.com/improperly-installed-low-e-windows/

He explains that in warmer climates, the low-E orientation is normally reversed, to reflect heat away from the home. And he finds it quite common to find windows which have it wrong.