Pedestrians Take Note

Do pedestrians get more stupid the older they get? Today I was driving in my car when I was approaching a set of traffic lights. It was early morning and the roads were clear and in the distance I could see an older female (old git some might say) about to cross the road. She had ample to time to get across but the fustrating part was the fact that she had pressed the button and crossed and of course, by the time I got to the bottom of the road it just decided to change to red. She had been safely across the road for a good 40 secs before I was anywhere near yet she still felt she had to press the button. Why? Isn't a little common sense enough? It is really frustrating as it wastes both my time and fuel just because somebody can't exercise some sense.