SUMMARY:
What service is it that does the Wi-Fi scanning on Android anyway?
http://i.cubeupload.com/lYvIsQ.jpg

DETAILS:
You probably don't know the answer but what allows WiFi scanning anyway?

In the past few weeks I changed so many things on my Android 4.3 phone that
I don't remember what killed WiFi scanning but I just want to ask, in case
someone knows, what actually does the WiFi scanning on an Android phone?

For example, I have over a half dozen access points at home, all being
broadcast in the clear, WPA2/PSK-AES protected, which the third part
programs find with no problem (e.g., Fritz! WLAN, WiFi Manager, WiFi
Connection, WiFi Analyzer, InSSIDer, WiFi Analysis, WigLe WiFi, etc.).
http://i.cubeupload.com/fV8D4d.jpg

Some (but not all) of the 3rd-party apps can find all the networks, yet,
the scan button in Android 4.3 doesn't find a single network anymore.
What on Android does the scanning anyway?
http://i.cubeupload.com/TNGRGg.jpg

I can certainly manually press the default Android 4.3 "Add Wi-Fi network"
and then it will connect to any network I manually type in, but it won't
*find* a network on its own anymore, even though the signal strength is
clearly in the negative forties, fifties, sixties, and seventies (i.e., the
signal strength is just fine).
http://i.cubeupload.com/lYvIsQ.jpg

I realize probably nobody knows the answer but just in case you do, what
service on Android does the WiFi access-point scanning anyway?