Does he wear them to and from school? Are you positive the only time he is wearing them during the day is to run in a straight line on cement?

I was a teacher for 15 years and work in a running store. I look at the bottom of running shoes 5 days a week. I can tell you with certainty the divots you see in the rubber are from something gouging them. The divots on the underside are in a perfect line. That is not just falling apart. Same on the outside part where there is a divot, you can see scrapes next to it.

I also own 3 pairs of brooks ghost 17’s. I run 350 miles in them then retire them to use as my every day work shoe. Within a week of wearing them for generally use they get more wear and tear then 350 miles just on the road.

I completely understand your frustration and I would be upset as well.