Same! Plenty of systems still use relays today such as the ... MTA Subway [0], ha. And elevators [1]. And definitely pinball machines [2]. And old telephony systems [3] although I doubt those kinds are still in service?

As far as I understand, some/many? industrial PLC systems are programmed using "ladder logic" which encodes logic as a (virtual) circuit of relays.

They were here before Shannon (used in telephone, rail signaling, etc.), got infused with math and a new meaning (formalized computing!) in his incredible master's thesis, and are still with us today.

My personal faves on the topic: Tim Hunkin's beautiful machines [4] which you can see in London, and his series on components - including relays of course! [5].

Cheers :-)

[0] https://en.wikipedia.org/wiki/Signaling_of_the_New_York_City...

[1] https://www.youtube.com/watch?v=wS3CkGzbsOo

[2] https://www.youtube.com/watch?v=uj8raZYHncQ

[3] https://www.youtube.com/watch?v=xZePwin92cI

[4] https://www.youtube.com/watch?v=dBbXkOY4oao

[5] https://www.youtube.com/watch?v=fdj_g_1tj4c