CAN is almost as old as Ethernet. While Ethernet where introduced in the 1980 and standardized in 1983, CAN where introduced in 1986 and standardized in 1992. So its interesting that a "very technical person" does not know established communication systems.
I don't find that interesting or unexpected at all. If you don't work in the auto industry (or where it's used elsewhere), your only introduction may well be a single slide in University. You can be a "very technical person" and not know what Docker or TCP/IP is either. Having no clue what ethernet is would be a bit odd though.
There are a ton of communications systems, just to name a few out of my head: RS232, RS485, USB, PS/2, Centronic, Firewire, I2C, SPI, JTAG, SPDIF, LIN, FlexRay, AS-i, Component, IO-Link.
CAN is also used outside of Automotive. Even Google is using it for their servers, or better for the redundant power supplies for their servers. HP is using it in their printers and copy-machines.
The thing is, there is always a technology you don't know. There is your preferred search engine and Wikipedia to help you with that knowledge, these days.
PS: These days almost everybody miss the difference between Ethernet and TCP/IP. While everybody talks about Ethernet most of the time TCP/IP is meant, not Ethernet.
I just joined a company in the automotive industry as have several others. Everyone who has changed industries to work for us has never heard of CAN or only know very superficial things about CAN. Improving the linkage to that body of knowledge is always welcome, including at my work.
That's to be expected. Even people within the auto industry only know superficial things about it. You can use can pretty heavily and not know much more than: "There's two wires, and you need a bus terminator"
