The airport debate continues

Felix Salmon follows up on his airport post and actually makes matters worse. He asks an expert (Greg Lindsay) what it is that makes the Hong Kong airport good and the response is efficiency. These airports are able to move people quickly and effectively (which, in the end, makes the travel experience more pleasant). But he concludes:

So I’m still not convinced that a major investment in airports is the best — or even a modestly good — use of federal infrastructure-investment funds. Yes, America’s airports are miserable places to travel through. But if what we want to do is boost long-term GDP, then there are better places for the government to spend its money. As and when airports get replaced and upgraded, they will naturally become more modern and efficient. Sadly, however, that’ll take time — and it might not make the passenger experience much better.

I wonder, in a time of low aggregate demand, why investing in more efficient airports is a less favorable form of economic stimulus than building roads or bridges? After all, construction labor is currently cheap and underutilized. Refitting airports so that TSA screening creates fewer queuing problems (for example) or to make them less vulnerable to delays due to poorly designed runways hardly seems like a bad use of infrastructure funds. And it will improve the passenger experience, if only indirectly by reducing the negative externality of lost time due to queuing issues (both of planes and people) that is currently imposed on passengers.

What is the comparison infrastructure investment that is clearly superior? I can think of a few transportation based ones (like improving public transport) but these often lead to new operating costs (running a new bus service, for example). Making airports more efficient might result in lower future costs due to more modern facilities and a better functional design.

What am I missing?