I have been NEET since dropping out of high-school in 2003. My first memory of being NEET was watching CNN (on cable TV in australia) and seeing tanks on high-ways rolling into Iraq. I didn't leave the house until around 2016, so no NEETbux or Autismbux for the first 13 years. I didn't even know you could get NEETbux for just being a drop-out until I read about it online like places on 4chins. So in 2016 I went to a Clinical Psychologist and they managed to get me on a semi-Autismbux payment, not the full payment, you need 2+ years minimum reports/evidence. I'm on my 4th Clinical Psychologist now because the first 3 said they have never seen anyone like me and don't feel experienced enough to deal with someone whose been shut-in hermit for so long. Oh, I saw a Psychiatrist and he flat out refused to believe Ive been shut-in NEET for 15 years, he claimed that just "wasn't possible". Yeah you gotta be careful when dealing with mental health """"professionals"""".
To answer the question: My parents have always been busy, doing their own thing, so I just fell through the cracks really, my siblings are all successful normies, good careers, married, etc, I think my parents just gave up on me and let me do whatever and just accepted the fact I'm autistic, but never bothered to actually get me any help for it. I assume to make themselves feel better about failing me, they just let me be NEET and not bother me about it.