I would be cautious about what people say in the survey on Stack Overflow. How many of those who claim to have ADHD or Autism have an actual diagnosis of those from a professional?
What matters for those type of surveys is how many people report struggles. If someone struggle with attention but does not have the exact number of symptoms required for a formal diagnostic, they are still struggling.
That people struggle is an important statistic, but shouldn't immediately be counted as ADHD or autism. There can be other factors at play.
"I have a concentration and/or memory disorder (e.g. ADHD)"
"I have autism / an autism spectrum disorder (e.g. Asperger's)"
Now that people are catching on to the fact they're not actually lazy but just have a much higher barrier to starting and maintaining focus on things they're not extremely passionate about some doctors handle 5-10 new patients a day.
ADHD is not rare. At all. The super strict guidelines exist because people are afraid of Ritalin and they're extra afraid of giving it to children, so double up on your "this is not actually a real thing" hysteria.