I'm pretty sure w3techs is just measuring who has what in their `Server` headers, so even a static site that happens to have mod_php available would still ping as PHP.

For the same reason, Python is virtually nonexistent—because nobody uses mod_python.

This one too: http://w3techs.com/technologies/overview/programming_languag...

This page was also interesting... Keep in mind, it's only the top 10,000,000 in Alexa: http://w3techs.com/forum/topic/22677

"In total, we have a few thousand technology indicators, many of them can be used - directly or indirectly - to determine the server-side language.

The number of sites where we don't identify any language is relatively small. The reason why we don't include it in the statistics is, that we want to show shifts in the relative popularity of technologies, not distorted by changes in our abilities to detect them."