Does a cochlear implant make a deaf person hearing?
No, a cochlear implant does not necessarily make a deaf person hearing. Each deaf person is different because the success of a cochlear implant depends largely on how well the brain adjusts to the new incoming information. Some deaf people can function as hearing with their cochlear implant but most deaf people function as a hard of hearing person. Some can understand speech with their CI, some can in a quiet room only, and some can't understand speech at all. If you know someone who uses a CI, it's best just to ask them how well they can hear with the CI. A CI also doesn't make a deaf person hearing because if they turn the implant off or if the battery dies, they are profoundly deaf again.
Do hearing aids make a deaf or hard of hearing person hearing?
No, hearing aids don't make a deaf/hard of hearing person hearing. While there are very powerful hearing aids out there that can dramatically improve someone's functional hearing, wearing a hearing aid is not the same as being hearing. Some people benefit more from a hearing aid than others. Some people can hear perfectly or near perfectly with their hearing aid but other people are still functioning with a certain level of hearing loss. This depends a lot on the amount and type of hearing loss, so if you're wondering about a particular person, it's best just to ask them.
Why don't all deaf or hard of hearing people use hearing aids?
There are many reasons why someone with a hearing loss might not have a hearing aid.
Hearing aids are expensive. Not all people can afford a hearing aid and most insurance companies don't cover the cost of hearing aids and many people don't have insurance.
2) Social stigma or Deaf Identity
Some people feel embarrassed about their hearing loss or don't want to have anything in their ears. As a result, even though they could benefit from a hearing aid, they choose not to. On the other hand, someone who identifies as Deaf, from a cultural perspective, may see using hearing aids as a way of sacrificing or trying to hide their Deaf identity, or they may simply see no point in aiding their hearing since they use visual language anyway.
3) Medical reasons
Some people simply aren't medically eligible for hearing aids. People who have a total hearing loss can't use hearing aids because they work by amplifying and shifting residual hearing. Some people get tinnitus (ringing in the ears or phantom sounds) from wearing hearing aids. Some people have tried many hearing aids and have found they don't help very much.
4) A combination of the above reasons