I haven’t done too much research into ADHD (which I don’t have) but if it’s anything like autism (which I do have) then it may well be that it’s just massively under diagnosed in people who aren’t rich, white, boys. I know they aren’t the same but that’s certainly the case for autism, and there is a high rate of co-occurrence between the two.

You’re not alone in thinking that, and there are some studies which seem to agree.