Hi,
Sorry to hear about yours and your son's struggle with bedwetting. My bedwetting started when I was a teen and has continued since then. For me it is not an overnight or even weekly thing, just occasional incidents here and there. Though my wetting is not frequent, I have, and still do, get frustrated, discouraged, and upset from time to time about it. So I understand these feelings.
As others have said your son will need to take some ownership in wanting to manage his bedwetting in order to be successful it stopping it, lessen it frequency, or have a positive plan for managing it.
This lack of commitment could be due to several things. For one it could be that he just isn't motivated to take ownership of it, though least likely I'd think. Another reason is he has given up and resigned himself that he will not be able to control his bedwetting or make improvements. Or somewhere inbetween these two thoughts.
Several things could possible help. Maybe a little counselling to help him recognize that first bedwetting, though very embarrassing due to society stigma about it, is really not that bad. As I has been mentioned in other posts there are a whole lot of other conditions and issues that are a lot worst and harmful to ones health.
Second the counselling might help him to recognize stage to managing his bedwetting. First is to take responsibility and ownership for and acceptance the he has an issue. Then that its up to him to manage his bedwetting by doing things like taking care of wet bedding and clothes in the morning, showering, and things like that. In the right mindset these actions of owning and handling his issue on his own can be empowering and motivating to go to the next stage of working towards a solution to his bedwetting.
Another thought is to not allow the doctors, family, or others say 'He'll out grow it in time.' This can be good advise when a child is young since it is more likely that it is true and the child will out grow their bedwetting in a few years. however for an teen and young adults it can come across as an empty promise since it does not seem to be happening.
Good luck to you and your son. Helping him to recognize that he can be empowered by taking responsibility for managing his bedwetting can be the start to his acceptance of his issue and working towards a solution.