I’ve noticed what the OP has. The Australian media certainly do it when a person is some dull age like 43 - it doesn’t have to be something relevant or important like 12 or 98. The only exception to this is in letters to the editor. These never have an age next to the correspondent’s name unless it is a rare example of a child’s letter being published, or a very elderly person who maybe writing an “I was there when…” letter.
As for general newspaper text though, it is a very common practice, and I think as much as anything, it is a style thing to help break up the article and avoid close repetition of the person’s name only a few words after a previous example.
Consider:
A motorist was arrested for high-range drink driving after police spotted his vehicle weaving onto the wrong side of the road in Sydney’s west today. Peter Sullivan returned a blood alcohol reading of 0.2, which is four times the legal limit. Peter Sullivan was charged at Burwood Police Station…
It doesn’t work as smoothly as:
A motorist was arrested for high-range drink driving after police spotted his vehicle weaving onto the wrong side of the road in Sydney’s west today. Peter Sullivan returned a blood alcohol reading of 0.2, which is four times the legal limit. Sullivan, 39, was charged at Burwood Police Station…
They often do it in specialty sections of the paper like sport or motoring, where they are talking about the same people and things day in and day out.
“Cricket Player X is making a good recovery from his elbow injury, his coach said today. The fast bowler is expected to play in next week’s test against England”.
Motoring articles really make me feel sorry for the jounalists, as the subject matter is so limited. In an article about a new model, you’ll see them mention the name, and then a sentence later it’ll be “this new addition to the stable” or “Detroit’s latest effort”.
It’s the same with the age thing. The papers will often have to resort to adding the person’s suburb or employement, but issuing this information slowly, one piece at a time.