Working in the medical device industry, I can tell you that making a medical device is HIDEOUSLY expensive.
The cost to produce a hearing aid (microphone, amplifier, audio tube, speaker, battery, silicone tip) is pretty tiny. If you were just producing this assembly you would probably be able to crank it out for less than $1000 with a fairly tidy profit margin - maybe as high as $500 (assuming you build them in quantity).
Now onto that cost add the FDA-Mandated record keeping (design history, a history of each device from manufacture to end-user distribution, including records of any time it came back for service/adjustment), performance testing, IEC/UL safety testing (to make sure it won't shock Mom's eardrum, or over-amplify and blow it out), IEC/UL electromagnetic compatibility testing (to make sure it won't cause Mom's pacemaker to go haywire), biocompatibility testing (what if someone is allergic to silicone?) and staff to oversee all of this, and all of a sudden your $1000 device winds up costing the consumer $3000, and you're still only making $500 in profit.
Hearing aids also aren't a growth market: There are only so many people who are hard of hearing and need the devices, and if they buy a good one and they'll keep it for years, so there's not a huge amount of recurring revenue for replacements, so now we need to make enough money off them to coast along until the next person needs to buy one.
Bottom line: Complying with regulations costs lots of money, and the cost of devices are inflated as a result.
Lest someone take this as an anti-government rant, it's not: The FDA regs do serve a purpose, though perhaps said purpose is not 100% appropriate for all classes of medical devices.
Also the FDA is not the only government agency that introduces a price-inflating regulatory burden. Consider these two identical aviation headsets:
The key difference between these headsets is a piece of paper. They are materially identical in all other respects.