Missing Avionics
Well, there is the bit of avionics kit we have (inexplicably) NOT got yet.
It is the sort of GPS moving map display, for taxiing, that I have when driving a car. With the aircraft position shown on the airport taxi chart. Why don't we have them? (or is it just me that doesn't?) It seems it would be really easy to implement, the whole thing could probably be done in software, for many modern aircraft.
It would surely reduce taxiing stuff-ups and runway incursions, particularly in poor visibility. And would compensate for all those airports where taxiway signage is piss poor. And would also help you find where parking stand Z-497 was located on an unfamiliar airport.