Finland had strong import controls directly after the war, so imported electronics was very expensive. Industry automation still used legacy hydraulic logic (fluidic logic) to control complex automation in pulp mill processes in 70's. It was very steampunk.
Pneumatic signaling has been commonplace too... set points for valves, etc. can be sent by varying the (low) pressure in an air line to the valve itself.
One downside to this is the case where there's condensation in the line and temperatures go below freezing. You can lose control thanks to the ice that forms. I remember this causing trouble with powerplants in the 90's during an ice storm in Houston (which is usually quite warm and humid, so they didn't think too much about icing.)
Yes, there's lots of building automation / HVAC stuff that uses pneumatic signalling/actuation (like the infamous T-4002 thermostat, look up images of it, you've probably seen it before!).
Amusingly enough, lots of those pneumatic systems use 3-15 PSI signalling, which works the exact same way that 4-20 mA signalling works -- with a live zero so breaks in circuits can be detected!
Early in my career, I did some work on what was essentially a Foundation Fieldbus to 4-20ma adapter. To get it to control our pneumatic valve for a demo, we wired it to a 4-20mA to 3-15PSI converter and then to the valve itself. It was a bit Rube Goldberge-esque, but it served our purpose well.
Automatic transmissions in American cars were used hydraulic fluid based computers in the 1980 - I recall taking apart a transmission with my dad and looking at the hydraulic controls. I don't know when they changed over to electronics, my guess in late 1980s. I suspect all auto manufactures stuck with hydraulic controls for a while - transmissions are ultimately controlling hydraulics so electronics didn't save complexity (CPUs give other advantages that make them worth it in the long run)
Finland had strong import controls directly after the war, so imported electronics was very expensive. Industry automation still used legacy hydraulic logic (fluidic logic) to control complex automation in pulp mill processes in 70's. It was very steampunk.
https://en.wikipedia.org/wiki/Fluidics
Hydraulic logic control is still a useful thing but nobody builds complex industry automation using them.
http://ph.parker.com/us/17567/en/hydraulic-logic-element-val...
http://www.logichyd.com/