Being able to "cut it closer" is not just a function of predictability, but also of frequency and of the consequences for missing your intended departure. If I miss the local city bus, it's not a big deal, because I can get another one ten or fifteen minutes later for the same price, so I usually only get to the stop about 90 seconds before I need to be there. During rush hour, I get to the caltrain about 3-5 minutes early, and in the evenings, when the trains only run once an hour, I aim for 5-10 minutes. But if I miss a plane, the next flight might not be for 6 hours, and it could cost me an extra several hundred dollars. So even if the airport experience is made more time-efficient, the nature of the airline timetable will still result in people waiting in airports.