That doesn't comport with objective reality where sex and gender are actually way more complicated things. For the majority of people, this is how it works; but that isn't how it works for everyone.
Even if we completely ignore the issue of trans persons and focus purely on things like chromosomes and anatomy, things can be
very complicated.
Here's an example: Androgen Insensitivity Syndrome (AIS)
Complete AIS means a genetically male individual (XY chromosomes) is by all outward observation female--they are born with a vagina, they develop secondary female sex characteristics during puberty. In fact, without genetic testing or checking to see if this person has ovaries (someone with Complete AIS lacks ovaries, they cannot get pregnant) there is simply no way to tell that they are genetically male. When they are born, they look female, so they are called female, they are raised as girls and become women, and they can go their entire lives not knowing that they are genetically male. The prevalence of Complete AIS affects is estimated to be between 2-5 in every 100,000 people
That's just one biological example of the complexity of this. We don't even have to talk about trans people, sex and gender is complicated.
Boys have a penis and girls have a vagina is a broad generalization that is
often true, but it is not
always true.
For a person with Complete AIS what do we use to categorize them: Their genitals? Their chromosomes? The presence or lack of ovaries? It can be very complicated, and overly simplistic thinking simply doesn't jive with objective reality, with biology, or science.
Also, the argument that this affects so few people, that it's just like 0.002% of the population or so, and thus is statistically unimportant doesn't fly here. We are talking about real people, not statistics.
-CryptoLutheran