Hearing and vision are both very sensitive senses, that are easy to permanently damage.

Everyone should have access to treatment they need, but having a licensed doctor review severe cases to find the right fit and prevent further degradation or full deafness, especially if their hearing is already weak, is a reasonable safeguard.

But also it's protection to prevent you from further damaging your hearing, just like most drugs require a prescription.

The real problem isn't the regulation requiring professional oversight of potentially damaging devices (or medications), but the fact that medical care is affordable for many.