You wrote "the test is quick, easy, and painless" but I also want to note that it's not always. Depending on your country, parents, specific doctor, etc it can be very difficult to get a proper diagnosis and help. In some places a big criteria is diagnosis during childhood so if you're 30 or 40 you might have no chance. Or a chance but it depends on your parents retroactively answering a questionnaire, or finding an old report card with the right words.
As you said it's life changing to get the right help and I encourage everyone to pursue this.
Btw no criticism implied on my end, I'm just now constitutionally incapable of not telling people they should get screened. Hmmm I wonder why I have difficulty resisting that urge...
The chance to be diagnosed with an appropriate gate varies greatly based on where you live and which doctor you can see and more. It can be anything from a 5 minute conversation, to 6 months of inconvenience, to no chance of even existing in your lifetime, to suck it up and don't ask because your career will end.
Huh? You don't have to be tested as-a-child, you don't have to call up your fourth grade teacher. You can self report your subjective experience.
"Did you have these problems as a child? Have you always had trouble doing your homework? Did stressing out about homework enable you to do the homework?"
They ask the question a few different ways typically.
I get it, perhaps it is different in your area, but I get the impression that an adult ADHD diagnosis is far from impossible.
In the US, at least, it ranges from difficult to straightforward, but that's not true everywhere