Primarily different regulations. Everyone interacting with a commercial oven is a trained professional getting paid to be there and the space is designed to a certified standard. This means you can focus more on pure performance and less on liability stuff.

And commercial equipment, because it needs to last long, is optimized for maintenance. I imagine insulation makes it harder to access and clean (or fix) the internals of an oven. Not to mention how often you’d have to change the insulation to keep your kitchen up to health standards.