Captured market. Some of the costs are paid by insurance, so it's seen as "not hurting consumers, since, hey! insurance pays for it anyway".
The article does mention this bit to sort of justify the cost:
> To get such a chair, a person needs a prescription, authorization from their insurance company, and a custom fitting from an assistive technology professional. Like a tailor crafting an exquisite suit, these technicians meticulously measure a client’s body to ensure the device’s specifications will match.
In many cases, yeah the wheelchair is specialized and has features that each individual needs. My friend with muscular dystrophy had one of those. But the drivetrain and the lead acid batteries seemed generic enough though possibly a higher quality, but it was definitely not something that should cost $65k.
