I totally agree that medication could be life changing for you and its awful its not quicker. But to answer your question 'why should we have to wait..' to put it crudely, because there is not enough resource to go round.
In terms of figures, NHS teams provide assessments of ASD (many hours of assessing with around 75% confirmed) and ADHD (shorter ax, 90% confirmed), provide prescribing, titration and reviews of meds, plus navigating meds shortages and change requests. Also transitions from CAMHs for both, liasion with other teams,advice and guidance to inpatients and screening referrals.
The average team in our entire regional area has figures like this:
Wait list has of 6000.
Referrals 200 to 300 per month, majority accepted.
Closed epsiodes of care around 250 per year. This is assessment complete, treatement complete, patient relocated or patient deceased.
Team of max 10 staff in a range of roles but all working on assessments or treatment. Remember no treatment for ASD.
This isnt 10 staff working all year either, there is leave, sickness, training, part time, maternity and vacancies in the pot.
I totally appreciate everyones want or need for dx is so valid for them, but this is not sustainable with these numbers.