I really don't know much about public perceptions on the traffic side, but where I live, people *love* to tweet photos of the train prediction signs showing something other than what they want. Some the time, this is not incorrect predictions but correct predictions of large gaps in service, which is immediately photographable thanks to the sign. Of course, unlike drivers, they can take such photos safely while waiting.

The nature of disruptions on rail is indeed different. You don't have nearly as much volume-based congestion, since every vehicle out there is, at least in theory, there because a schedule said it should be. (However, at junction points, where trains have to take turns going through, they can experience non-linear congestion effects if they're on high-frequency lines and even one falls behind schedule.) So, absent disruption, the travel times are generally less variable than those on the roads. On the other hand, when a single train breaks down, has accommodate a sick passenger, or has to stop for any other reason, nothing's getting by without crossing over onto the opposite tracks, resulting in significant, difficult-to-predict disruption in both directions.