My step brother is 24, a drug addict, illiterate, has no concept of basic maths (can add things on his fingers to the value of 10) and never lasts more than 1 shift in a job because of his anger issues brought on by the need to feed an addiction that he cannot feed until the end of the shift. His pathway plan is to overcome his addiction, see a psychiatrist, do a program the the drug and alcohol place, and learn very basic maths and English. After he learns to read and write he will do a computer course which will hopefully allow him to take on some work if it co-incides with him winning his fight over addiction.
IMO he is the perfect example of a special needs child abandoned by one parent and ignored by the other. His problems as a child were similar to my brother's problems. They are a similar age and grew up in a similar area. His mother is a teacher. She should have known better than to ignore him.
We pushed for help and when my brother wasn't getting it at school, he got it from home. We set up tutoring, psych appointments, extra activities that could assist with his school work, his mother did diddly squat.
Part of what my step brother does to receive the measley amount of Newstart Allowance he receives is to be drug tested (organised through the job network liasing with psychs) and attend meetings for his addictions. So it is in place for many who need it. I doubt it would mean cutting off his payment but maybe after being in meetings it would lead to rehab then maybe come down heavy on him.