First of all, chances are, you are required to save receipts and may be required to send them in, even if you pay with your flex debit card, for proof of correct use.

More importantly, whoever accepts that debit card will use a service for processing. Each business has a different sic code, and it is possible that your flex account only accept certain codes. Case in point:  I tried using my flex card years ago to pay for a dependent's braces at BU Dental. Even though it was a legit expense, the card was declined because the provider was classified as a school, and not a medical practice.

I suppose it is possible to find a provider that is properly licensed and able to take that card in payment, but my guess is that it will be a big stretch.

You can also use it for laser eye surgery, potentially hair transplant with Dr. Leonard, or some other medical use for something that may ail you.

Actually the right-wing Heritage Foundation came up with the basics of it and Romney picked it up. Strangely, they started hating the mandate once Obama picked it up.