They’re a dumb fan that thinks it’s smart.
They have a relay for the high current feed, I think this is to limit a return spike when the motor stops.
The motor housing contains the pictured module encased in rubberised beige epoxy (mongrels!). Of the five pins, four are used - power and ground, control (modulation) signal and return signal. It’s like a 200A version of cabin fan controllers. I presume the choke visible is to restrict spikes, too. The fan when working, only operates low or high speed, it doesn’t pulse or vary beyond that.
Of course, a bit like BA steering columns, you have to buy everything in event of a failure - not just the motor.