I first learned Python (which I use for web-related functions) from an engineer at Seagate who uses it everyday in failure analysis of drives (they use something like Python 2.2 still). That's something I always loved about Python -- it can be used for anything. It may not always be the "best" language for the job, but you can always "get it running" in Python.
If you search for 'PHP' you get goose eggs too. Does anyone know if language names are intentionally filtered out of career searches at Facebook? 'GIS' and 'Logistics' work as search terms.
(Work at Facebook, but not on this system, and know nothing about it.)
It looks like the search matches on job title/position, and not content. That does seem a bit unexpected.
In general, Facebook does not place much emphasis on programming languages that people know before they start at the job, and part of the Bootcamp process includes the expectation that people will be learning at least one language they don't know (unless they already know C++, Java, PHP, and Python at a production-code-writing-ability, and then they'll have to learn our libraries anyway).
We obviously discuss the languages we use and what we use them for during the hiring process so that people know what they're getting themselves into - people might be looking for something familiar to ease themselves into it, or they might be looking to explore a new language when they start.
(Yes, we use Python for a bunch of stuff. And I know we had a few people working on talk abstracts for PyCon to try meet the deadline that explore a few ways we use it.)
I believe our mentality is good engineers want interesting problems to solve and can learn any language. We're interested in what you've done, not the language can do it in.