2.4GHz RC cars and WiFi, A history and Investigation

This all came about because of my little hobby of reworking RC cars to be controlled by Raspberry Pi computers.

An early aside: In my last iteration I discovered that not all Wifi dongles are capable of being configured as Wifi Access points.   Here is how to discover that:
  https://wiki.archlinux.org/index.php/software_access_point

OK, I recently picked up a car that is labelled 2.4GHz and I wanted to know if I could connect to it with my Android tablet as I do with my other experiments. Neither Fing or Wifi analyzer programs would 'see'  the car. I begasn to wonder if perhaps it was using a different  2.4GHz physical layer, not DSSS (Direct Sequence) as I was used to in the old days of Telxon. The manufacturers of these cars do not give out any information about it, I can't even find a configuration manual.

This got me wondering what the current way of using wifi is, so I found this: https://en.wikipedia.org/wiki/IEEE_802.11
It does not mention in detail where these variations are used.

I started looking at the history of Wifi to see if there was anything there and found that the recorded history does not fit with my memories. https://en.wikipedia.org/wiki/Symbol_Technologies is  the view from a Symbol  Technologies viewpoint and this leaves out such a lot: http://www.fundinguniverse.com/company-histories/telxon-corporation-history/

Telxon acquired Telesystems Corporation. Their first offering was in the 900MHz band, but they soon moved up to the 2.4GHz band, though the radio was quite large to fit into the form factor of a Telxon PTC. I think this radio was called the 022 version.  They wanted a smaller radio and soon there was the 025 radio which was about 1.5 inches square and fit very nicely into a Telxon PTC.
What isn't mentioned is that Telxon sold the wireless division now called Aironet, to Cisco. This is mentioned here: https://en.wikipedia.org/wiki/Aironet_Wireless_Communications

Things have moved on since the great DSSS/FHSS fights with Symbol and now it seems that the common mode is OFDM   Orthogonal Frequency Division Multiplexing.

My investigation found this site that discusses the fact that different manufacturers use different forms of Wireless, some DSSS and some FHSS and some mixed, and that they are not compatible with each other, so the receiver must match the transmitter.
http://rcmodelreviews.com/spreadspectrum01.shtml  You need to get to page 5 at least.

Enough.