They have them actually. Well, not the air bag, but they have pants with padding. My friend cracked his tailbone riding, and I said, "screw that" and spent the money on Demon FlexForce pants. Best money I ever spent (well outside of the helmet).
If you’re feeling frugal and not particularly proud, you can cut to fit one of those foam rubber sleeping pads that folks use for camping when they don’t want to swing for a Thermarest, and tape the cuts into the rear and knees of your snow pants. It doesn’t look great, but it looks a heck of a lot better than bruising.
It is for beginners - you get over that. Learning how to fall by kind of sitting helps.
When I lived in Chamonix a lot of the enthusiast boarders had fractured spines - now there's one to avoid. Mostly from going over cliff like drops by error, off piste.
