Time and effort to sell is also cost

What’s wrong with having boundaries?

Do you mean BAHA (bone anchored hearing aids). In this ,you still rely on amplification by means of a piece that’s anchored either magnetically or surgically to your skull.

Cochlear implants function completely differently in that there’s effectively a new pathway to the cochlea (it bypasses the damaged parts and goes straight to the inner ear structure). You have to learn how to hear in this new way.

How come?