Hi DiveMom1,
First, let me thank you for starting this discussion. And, while I'm at it, thank the ScubaBoard community for posting, in general, positive and helpful posts to work this through with you.
I continually find it alarming when a diver takes being in the underwrater environment too casually. Yes, there are a lot of approaches that you can take to facilitate your husband having a more responsible view of the sport and it sounds like you and Jim are well on the way to working through ideas.
Your reference to driving is interesting... As I see people driving and shaving, or doing makeup, or reading reports, or texting, or... you get the idea - it seems that it is a similar problem of taking the environment they are in (whizzing down the road at 100 KM/Hour) too casually. It isn't that one needs to have a hyper sense of paranoia - this can and should be a fun and safe sport, but everyone should have a healthy respect for the environment they are in. Perhaps it may be helpful to frame a portion of your buddy skills workshop in this light - not that buddy skills need to be done because any given expert said so, but because the environment we are putting ourselves into is not one that should be taken casually.
Kudos on working with your kids and keeping them practicing skills as they dive. Sounds like you are being a good buddy and good mom and keeping them aware of the challenges that can occur in this underwater world.
Also, do write your letter to the shop - it can't hurt, but let me add to the voices that say it is a good call to avoid a shop that doesn't have an appropriate perspective on the sport they are teaching. Their students are likely unaware of the risks that they are being exposed to.
Safe diving!