It would be interesting to know the 'flow' of shop teachers in today's system. Are they accredited ('regular') teachers who took a course or two for further accreditation, with or without some inherent interest and skills, or did they come from industry and jumped through the regulatory hoops. As I mentioned - somewhere - back in the day, all of my shop teachers came from industry, and my high school had every shop imaginable (wood. metal, electrical/electronics, auto, HVAC, construction, and I've probably missed a few). I'm not sure they exist to that extent now. I know my daughter's high school had wood, metal and auto but I don't remember if that carried over when they built the new school.
When I took a small engine night course at a community college it was a non-credit course so they could hire pretty much anybody they wanted and our instructor was a m/c mechanic by day.
Interesting question and it might have personal considerations, such as home life (tired of chasing work, looking for regular hours, etc.), health, etc. Back when big box reno stores first broke into the Canadian market, like Home Depot and Rona, a lot of the employees came from the trades. The ones I spoke to had simply retired but some had health issues that prevented them from some physical aspects of their trade. Of course, most of that is gone now since they mostly hire part-timers who have little clue.