I was 33, and the person who had the job before me was a year or two younger when she got it, as was my current boss when she became a 15 years ago. I started as a 13 when I was 28, but they were both in government from right out of school.
I've noticed that people who make 15 young tend to move on, which opens things up for others. Also, on the topic of envy, I like my job but there are tradeoffs and, at least from what I've seen, most people don't want the job when they see what's involved.