I've heard the phrase "disability markup" used to describe how almost everything ever targeted toward physical or sensory disabilities are absurdly expensive. That name implies more intentional malice than I expect is at work; I'd generally round off to "market forces"--it's difficult to take advantage of mass market capitalism when selling to a minority, but it is possible to take advantage of government assistance programs.

It seems like, though, based on my (very limited) understanding of hearing aids, a charitable version of "disability markup" might be closer to reality. After all, if it's treating a disability, especially one found in old people, either those who need it are going to be rich from a lifetime of savings, or poor and getting the government to pay for it anyway, right?

It isn't hearing aids so much as screen readers, but Chris Hofstader implies as much might be a component of business models for such companies in this article:

Will FS respond to this new found competition, possibly based in the fact that NVDA costs nothing and FS gets more than a thousand bucks for JAWS with a price cut? Probably not. I haven’t worked at FS for more than a decade but, back then, we discussed the possibility of a free or no cost screen reader coming onto the market and how we might respond. Our strategy then and likely now was that, if we felt competitive pressure from a low or no cost solution, we would raise the price of JAWS. As I mentioned a couple of paragraphs ago, there are technologies that one can only access using JAWS and the FS strategy was to make sure we kept our profits high by “eating the rich.” I don’t know if FS will respond this way ten and a half years later but, as NVDA RA adds a feature to NVDA that one needed to buy JAWS to get, , they may need to find a way to replace the dollars on their bottom line and may, in fact, respond by increasing the price of JAWS.

James_Miller's guess wouldn't apply so much to screen readers (but would apply to things like the Brain Port, which opened at a price of $10,000US), but I wouldn't be surprised if going through the FDA is a big part of the markup on hearing aids.