Here’s a 2012 article from Podiatry today.
http://www.podiatrytoday.com/article/2012
I think the major component is that they need the extra depth for the custom insoles. There are people that need custom Diabetic shoes but I can only guess there are people that could do with a proper fitting comfortable sneaker type shoe (New Balance white shoes).
Then there’s the “business” side of it:
From the article
"6. Medicare reimburses approximately $300 for one (off the shelf) pair of extra-depth therapeutic shoes and three sets of heat molded/custom multilaminar insoles. Your cost for shoes and inserts can range between $120 to $200. If you don’t provide shoes for your patients, someone much less qualified will. "
Approval would probably mean going through the process of the correct medical departments/agencies and their checklists. I think the article touches on that point.