Which part of my question are you having difficulty understanding? If this is so important and accurate surely you can name and explain the important and accurate tests, and their results. Maybe it isn't as simple as you say?

Why should the simplicity of the definition (which, by the way, is what sex means in mammals generally, not just in humans) mean that the testing has to be simple in 100% of cases? I’ve already described cases where it isn’t. That doesn’t change the definition.

Do you think natural phenomena don’t exist or can’t be useful unless there is a simple test to grant you the details?

I think there are tests that intelligent people can describe which demonstrate the phenomena exists. That's what science is.

I think my answer was larger than the box you drew for it, and now you’ve sealioned yourself into a very weird corner where you seem to think the existence of male and female developmental pathways is somehow negated by edge cases.