One possible reason for lack of interest is people not wanting to get their hands dirty, but another possibility is how much they would earn. I don't know if BJ's pay good money or not, but that would certainly be a factor in being a company people want to work for.I find it hard to understand why younger people would not want to acquire the skills involved in frame building.
Getting decent trainee staff in any hands-on job seems to be very hit and miss these days. I've personally encountered some real dross over the last few years, either lazy and unreliable or totally cack-handed - or worse still, both. It's so bad now that when you do come across the odd decent trainee who doesn't mind grafting, it really stands out.