Hope that helps a little to explain the difference. This is also why you can’t really have a hearing impairment aid without doing the assessment which it sounds like Apple can now do with just the AirPods and an iPhone, because it’s never just “tuning up the volume”
hearing aids are medical devices, not headphones with passthrough.
The tolerances of safety and robustness alone are worlds apart.
Think about it this way: if a pair of apple earpods break, you just buy another one.
If my hearing aids break, there is a very high possibility of death and dismemberment leading to termination of my life.
Also, I would never buy apple branded hearing aids except under the circumstances where Apple and the FDA come to agreement, contractually obligated by the US courts system, that if Apple decides to terminate that product line, that all information, patents, design schematics, and code are passed to a 2ndary company (it could be one of the current hearing aid manufacturers) for continued support.
There can absolutely be no instance where apple can decide to "lay off the department" and "turn off the update servers" and leave the product unusable, for the lifetime of the patient.
That's the real difference between hearing aids and headphones.
I use hearing aids, and without them, my workplace turns into a death zone.
Think about people working in public transportation with hearing disabilities.
Imagine if you are working in an Amazon warehouse where your hearing aid fails and you can't hear a mechanized forklift coming through, or you can't hear announcements pertaining to safety.
Even at regular office, I can't hear fire alarms without hearing aids so literally, if the hearing aids fail, and there are no flash alerts or smoke alerts, I'll just keep working through a fire alarm. Thankfully flash alerts are regulated and mandatory.