Technology

If by discrete ICs you mean custom logic baked into silicon, yes that's always been expensive. I was referring to off-the-shelf ICs that cost pennies, which used to be orders of magnitude cheaper even than PICs (in the days before Internet connected fridges).

Before the term software engineer was commonplace, electronic engineers used design circuits around off-the-shelf components, like the venerable TI 555 timer or op-amps, and design a circuit around them. To do it they'd need the datasheets (https://www.ti.com/lit/ds/symlink/lm555.pdf). Hobbyists and aspiring young engineers would buy books like this: (https://www.computinghistory.org.uk/det/14021/IC-555-Projects/), which were like O'Reilly cookbooks for electronics circuits. The equipment to program a PIC used to be way beyond the reach of hobbyists, and wasn't necessary for manufacturers producing simple control circuits. If you look at circuitboards from that time you'll see some ICs with pins that aren't connected to anything because those just weren't needed for the circuit, much like you describe the empty sockets in modern boards.

It absolutely was possible in the pre-Internet days to design a fully functional fridge, and more, without writing code of any kind, and it was cheap too.