On reflection, I couldn't be sure whether my irritation was triggered more by my time being wasted or my judgment of his behaviour as "unconscious". My irritation doesn't really matter in the greater scheme of things: it is mine to deal with along with my demands that things should be different and judgment of how people should be and behave.
So the incident cost me a minute or two of my time (which happens to matter to me), but it also cost him some time in his own life and perhaps even a moment of anxiety at keeping a toll booth operator and finger-tapping driver behind him waiting. Perhaps he chooses to live his life that way and doesn't particularly care that he doesn't plan for what lies ahead, or that he is insufficiently organised to know where his money is, or who might be waiting for him to live his life. (I can hear my own judgments ringing out as I write, but just indulge me for a moment here!)
I find my buttons also being pressed by people who bump into me in shopping centres because they're texting and not looking where they are going, and people who drive erratically because they're lost or unsure of where they should go, and people who call me Mike minutes after being introduced to me as Andrew Pike, and families who spread five wide across shopping mall walkways and dawdle along, so no one can get past, and people who use their cell-phones at the movies, and, and... (Feel free to share your own examples.)
This is all called unconscious living: people who are so engrossed in "I" that they are out of touch with others and the context in which they are living their lives. There is a huge inefficiency about living one's life this way. The costs include loss of precious time, disconnects with others and not engaging fully with the wider aspects of Life. For instance, I refuse to believe that it's only me who feels irritated by others acting on automatic and impacting my space and time. I think there's a whole bunch of us who get irritated and feel alienated by that behaviour. I guess that's why we see road rage, which is just a very dramatic form of irritation at others' unconscious driving. If I am right, much as we can try and be saintly and forgive and surround the unconscious person with pink light and so on, the fact is that the unconscious behaviour still creates a pretty big body of people who feel alienated and disconnected.
I'm not suggesting that we need to live our lives in super-efficient, perfectionist mode. All I'm suggesting is that we all catch a wake-up!
For the meantime, I'll renew my efforts to achieve sainthood. I seem to have lost some momentum.