If sex can only be determined through a chromosome test, and every other sex-indicative trait is deceptive, then, by that logic, all but a tiny handful of people who have had their chromosomes tested have no way of knowing what their sex is.
Some folks want to say that is a "scientific" definition of sex, but it has no relationship to how sex is or has been defined and determined socially or medically in the real world.
Children are not given chromosome tests before their sex is assigned.
@DavidSalo Careful you'll make heads explode. They claim simple test and you follow up with assigned at birth.
@Ruthat @DavidSalo Well, and there are the 1001 ways genes can mutate or move that create havoc so that despite being XX or XY, all of the other secondary sexual dimorphism appears to be the reverse. They need to stop digging, admit it's not simple and get their hands out of our collective pants.