I suspect what's most likely is that more people who are not eligible for the tax credit, but do have diabetes, are being coached to think they can apply for the tax credit by companies that get paid to help them apply for tax credits.

A growing business teaching 'how to win at taxes' would result in more spurious claims, and has little reason to comfort those who find out they weren't eligible. Instead, a company that gets paid to tell people how to save money (even when their advice is bad) can simply deflect the anger of the customers they've cheated at the government, even without their own staff being aware that it's company policy to lie to customers.

This is speculation, but I like the 'evil businesses who just want money' concept a lot more than I like the 'evil government who just wants money' one, because the latter makes no sense to me. The government has much more to lose if they cheat voters than a business does if they scam customers.