Journamalism Question

Why is it that when non-famous people are quoted in the news media, their ages are always given? Just about every story in the paper features a sentence like:

“Of course, I’m aware of the wave nature of matter,” said Tallulah Johnstone Black, 47, a homemaker from Waterloo who witnessed the incident while walking to the store, “But I never thought I’d see an elephant diffract.”

Unless the story is about age specifically, I don’t see the point. What am I supposed to do with that information?

Stranger still, the one time I was interviewed by the police as a witness to a “domestic disturbance” across the street, the cop made a point of asking my age. Not date of birth, or anything that could be used to confirm my identity, but my age. Why?