"I'd wager a large percentage (if not a majority) of age 50+ men in the US have them done"
In my sample group, it's not as large as you think. I'm a 43 year-old post-vasectomy father and out of a group of ten close male friends/relatives I've encountered 2 close calls and 2 oops babies. And these are intelligent responsible men. The majority of the excuses range from "I just never got around to it" to "I don't want to get cut". Seriously?