I think that CAT IIIc requires taxiway "localisers", as <75m rvr is the objective. The a/c can land in 0m its just us pilots that can't see to taxi as you are well aware. Therefore taxiway guidance is needed, as far as I know the cost of the infrastructure required, stopped most airfields implementing it. It requires the taxiways to be excavated and the guidance inset in the tarmac(Best solution at the time) to insure that interference of guidance did not occur. Furthermore, the tower were unable to observe A/C taxiing, also in the event of fire no services could reach the a/c and it required a constant commentary by the ground controller using the ASMI to get the services to the a/c. All of which (at the time) was deemed too expensive/complicated, so failed the cost/benefit analysis. Most airfields only experienced the weather phenomenom rarely, and often at times when no flights were operated. Thus further negating the need for the technology.
A bit rambling but hope it hepls, happy to be corrected.
[ 28 September 2001: Message edited by: fadec_primary_channel ]