I believe that is a setting/option on the Hy-Tek results output. I'm assuming becausu Hy-Tek is an American company that Avg Mile is the default and it wasn't changed before outputting the results.
This question is for the statistician. Why is average time per mile listed and not average time per kilometre? The races are held in increments of kilometres - 3K, 4K, 5K and 7K. Average time in Kilometres would make more sense.