An audiologist should be able to tune your hearing aids to amplify only those frequencies that need amplification.
(Although my understanding is that this is fairly new, and may not be available around the world)
But the serious problem with hearing loss is the "bandwidth", meaning the damaged cells send less information to the brain even if attenuation is compensated by hearing aid, leading to bad recognition of sounds and speech.
An audiologist will typically test someone, see that they need amplications across the range but send them away with a much lower amplification for a weeks to get used to things. Then bring the volume up as time goes by.
People amy also need to get used to the aid's noise reduction algorithms as they can seem unatural at first and is a nightmare for anyone who used to wear an old analog hearing aid with no noise reduction.
So, yeah, hearing aids are rarely plug-and-play from day one - the user needs time to adjust.