Why is there no instrument taxi system for low-visibility operations?
If I were an airline executive in charge of determining the configuration of new aircraft being ordered from a manufacturer, and one of the options was an instrument taxiing system to allow so-called zero-visibility taxi, the aggregate cost of that system (purchase, maintenance, training, fuel to carry it) would have to be very low before I would consider it. My initial thought would be to reject it out of hand, but perhaps the ability to help a taxiing pilot navigate the taxiways of an unfamiliar airport would bring me around if the only cost was additional software for existing equipment. I say this as a pilot who on his first trip into Chicago O'Hare succeeded in getting some deservedly unkind words from a ground controller when I didn't turn when I should have and necessitated the rerouting of other aircraft.

In 10 years on the 747 I only once called for a follow-me car because of low visibility, and had the taxiway been better marked or my eye level lower I might not have needed that.


  So it wasn't worth it even for airports where crap weather is common?


Consider the Arcata-Eureka Airport in McKinleyville, CA. The airport was deliberately built during World War II where they could depend on it being very foggy, and in that they succeeded. While the approach and landing were often challenging, there was never any real difficulty in taxiing if you were familiar with the airport.