I appreciate the optimism (and do think there's some room for efficiency improvements!), but each step is a little more complicated than that. a true audiometric room/booth to do the testing (eg fully soundproof) in is very rarely found outside of audiologist offices or specialized academic spaces, for starters, and I do believe those are required for paperwork (whether it be insurance related part of the process to getting the right device fitted).
then there's also additional complications like types of hearing loss impacting calibration - some people react very negatively to higher (or lower) frequencies than others do, to the point facial stimulation can happen, and some people just have a frankly tricky profile that requires a trained audiologist on hand to work with them through several sessions, if not outright yearly on top of that, since the nerves and brain output can change by itself.
(source: have a cochlear implant, been doing the described experience since I was ~ 3yrs old.)
To add to this — I suffer from Ménière's disease, which manifests for me as variable hearing loss. Some days are bad, and I can hardly hear/understand speech even when someone is right in front of me and I can lip-read. Some days are good, and my hearing aids are uncomfortably loud or make things sound "weird". But most days, my hearing aids do exactly what I need them to :-)
I've had audiograms taken on moderate and bad days, and the difference in frequency response was significant (up to 30dBA difference across only the lower frequency bands).
then there's also additional complications like types of hearing loss impacting calibration - some people react very negatively to higher (or lower) frequencies than others do, to the point facial stimulation can happen, and some people just have a frankly tricky profile that requires a trained audiologist on hand to work with them through several sessions, if not outright yearly on top of that, since the nerves and brain output can change by itself.
(source: have a cochlear implant, been doing the described experience since I was ~ 3yrs old.)