Deborah, this was a very insightful and interesting post.  It may also point out that when you are looking for opportunities to do good, you will most certainly find them.  And when you find them, you need ACT right away because the opportunity is fleeting.  In each of your examples, there was a split second where the good citizen could take action or not, and without much hesitation they did.  Thanks for observing and, more importantly, acting.