Why are Harbeth speakers expensive while its drivers are not.

Well this is interesting. 

It seems to obvious to suggest that perhaps those far more expensive drivers would not...
A. Sound as good as the ones Harbreth uses.
B. Match the crossover.
C. Are as reliable.
D. Are as musical sounding.

One further thought. I wouldn't expect a speaker manufacture to change out drivers overtime the driver company called to say they have a newer " better sounding " driver available. 
Further the speaker manufacture, Harbeth in this case would have to change the model or put a II after it to designate the change. 

It is not always about $$$$$. How many of you think that if these " more expensive drivers " would sound amazing that Harbeth would not use them. 

I don't.