They generally use fuzzy logic to better drive various components with minimal BOM. You can easily encode a bunch of rules from expert on best decisions given certain conditions (for example for motor control for best efficiency, or heating, etc) and use fuzzy logic to switch between modes smoothly.

I remember reading about dedicated fuzzy logic circuits which essentially gave you simple fuzzy state machine programmed with cheap ROM, and it was all you needed instead of MCU for many tasks.

In a way cheap powerful MCU are biggest killers of the technique.

When I used FL during uni mid-90s it was used to optimize revolutions and torque for shifting loads. Another often described use case was a loaded cat on the arm of a crane, that moves along the arm without getting the load to swing.