My hypothesis is that planes are just as often late but people complain less because :

    1. They have already taken the whole day because getting to the airport, booking, security... so they don't care as much about a two hours delay.

    2. They have some respect for the fact that we are allow to fly and see that as big technical challenge depending on weather and good security practices. On the other hand a train *seems* trivial when in reality it's not. Psychologically for most people it's just putting some cars on rails and it will basically drive itslef to its destination.