Quite frankly because if it extreme ND the mother would be writing a lot more than the fact that her son seems incapable of getting oil of his hands and does not wash up plus has no friends.
Not one of things are criteria on a DSM 5 assessment for ASD ADHD or Motor issues.
They might be a symptom of them but not ticking the diagnostic box. There would be lots of other things she would mention which would tick the diagnostic boxes and I assume you must have said to get your diagnosis.
Lots of people are heavy handed or have no interest in going out etc. lots of people act like they for other reasons eg depression or just because they can’t be bothered or frankly are lazy and think that if they do the job badly they won’t get asked again. Who knows what is happening here? You don’t and the mother does not which is why there are diagnostics.
I’m not going to infer SPD or ASD from scant information.
Moreover if anything the employers would he raising issues or have awareness - he works in a dirty and most likely noisy factory. There should be some ASD triggers there! As part of a gold standard diagnosis (NHS) they look at other settings eg work or the gym etc
Im not saying it’s not but the OP has had every opportunity of giving more illustrations and even then the advice would be to engage with son and encourage him to wash up etc uses post it note reminders etc.
There is no magic help in this situation. He’s unlikely to want to be with pretty higher needs ASD people on a life skills course.
Even with a diagnosis she would not get any help o imagine from services as such. So rather than trying to make a point with me why not suggest to the Op what can be done to make her son do housework as there are no magical agencies that will resolve these for her even with a diagnosis.
So all it is are prompt cards, memory aids etc
Frankly if he wants a packed lunch she can stop buying the things he cooks and tell him to make a sandwich or buy a pasty from a nearby shop.
If my son refused to wash up I would refuse to cook for him - he is excused glass objects and larger items as he can’t handle them but he can wipe surfaces and tidy up
My son has broken parts of the hoover so I supervise and prompt or set him other tasks eg dust the cupboards
put a card by the sink with words ‘wash your hands’
She can refuse to wash his clothes unless he brings them down to the machine. I would watch him load the machine to understand what the issue was as using the correct force can he learnt or he can bring down everyone’s laundry instead and help that way. There are alternative for him to try.
he could be encouraged to join a Drama group.
there are ND groups set up in areas.
Close supervision would rapidly determine what is happening with house work eg my son extends the hose of the hoover as he can’t get the right force to push the brush and that bends it.
Even with marked ASD etc the OP’s son needs to try his best but as yet she has not ticked an actual diagnostic box.