¹ Maybe it is. I’m not an expert on the USA’s health and government policies.
Excessive regulation has created oligopolies and kept prices high in the US. The OTC hearing aid category is meant to help. Before that, low-cost devices tended to remain niche.
OTOH the regulation(s) were introduced due to blatant sales of substandard devices, esp in the 1970s. A high-amplification device runs the risk of further damaging your hearing. Many hearing aid users are vulnerable elderly.
There is a risk that you never receive the clearance or approval, but in this case Apple probably knew they had already addressed any feedback the FDA had so it was very likely there would be no further stumbling blocks
Novel devices have a different path.
Once cleared the FDA can and will come by at anytime and do an audit of your processes and if they aren't up to snuff they can shutdown sales.
Its a trust but verify system.