To me the industry exemption makes allot of sense for many engineers. After all, who would be the governing authority and what design codes would be used for go-carts, garden tractors, shrink wrap machines, and so on. That's not to say there aren't industry standards, but it just doesn't seem to have much in common with the process used to design buildings and such.
What does bother me are the companies that either ignore or abuse design codes using the excuse that they are exempt, when they probably aren't.
That's just an observation however, based on the experience of one person, me.
Regards,
-Mike