I'm not a fan of the bunt either but consider that "the book" assumes equal hitters. If you have a very weak hitter (like an nl pitcher) the bunt can be a good play because you give up an out but that guy might have made an out 80% of the time anyway.
At amateur levels below strong D1 there may (or may not) be enough of a talent drop off within the teams to make a bunt worth it.
But I wont rule out that the coaches are just ignorant either.