Light rail is used very well in many cities around the globe. International Airports in China for example use them. I would rather use one of those than spend 30 minute to crawl a fe KM and sit in Mount Victoria tunnel.
I agree with your comments on light-rail.
But ... I regularly commute via Wellington Airport and I can't remember ever having a 30 minute car ride to the CBD. It's usually about 20 minutes during peak times.
I've also never seen the traffic sit stationary within the Mt Vic tunnel. The bottlenecks are merge points just prior to the tunnel in both directions. Traffic actually within the tunnel seems to flow OK, even during peak times.