That is exactly why machines are not there yet. Because if it was a tick box exercise then you're right, machines could do it already. This is exactly how the private clinics screen for whether or not you should proceed to diagnosis, and it's pretty good in terms of accuracy - over 90%.
For more depth, there are already computer tests that you can do for ADHD, testing things such as working memory, reaction times, split attention and so on, I had a doctor who was very keen on me doing them and I did them about 3-4 times on different medications which he claimed was the gold standard way to test the medication. However, I did not agree (based on my experience at that time and also later, titrating medication in the usual way), and according to experts, these tests are very unreliable in terms of predicting the level of impairment in the real world, which is also what I found. Apparently the tests are more likely to be testing something similar to IQ - great for data nerds, totally useless on a day to day scale unless you are comparing two people with vastly different IQs. You'll see a difference in functioning between someone with IQ 70 vs IQ 90, but not very much difference at all between someone with an IQ of 90 vs 100, and even if you have an IQ of 130+ (classed as gifted) this is no use in the real world if you have severe social anxiety and cannot cope with normal social interaction.
I do think that in the future (not yet) bots similar to Chat GPT but much more advanced in language analysis would be able to interpret different patterns in how people talk about their struggles in the case of different issues whuch can look similar or cause similar issues e.g. ADHD, ASD, OCD, depression, anxiety, etc. And there is potential for machines to become even better than humans at this - humans tend to get a bit stuck in "hammer and nail" thinking where we are quick to recognise things which mirror our own experience, expertise, etc. So if you have an ADHD specialist they may be predisposed to see ADHD. Being able to "speak" to a machine would in essence be like having a whole room of experts on different conditions who can all see the signs of their own condition and come to a collaborative conclusion, which would be absolutely incredible medical care but not physically possible using humans - there are too many patients and not enough specialists (or time!) for this to be realistic. But as said, this is far away. Don't think of the current language models when you think about this.
You could then have one more general clinician who can help the person understand what the machine is saying and guide the person in deciding on therapy, treatments, management etc.
Mental health is currently so incredibly undersupported/poorly supported that it would be brilliant if there was a way to make mental health support available on demand to every single person at all times.