The prevalence of being intersex/having a disorder of sex development is just as high as the prevalence of being trans. Both of them sit at around 1-2% of the population. That number may be surprising but in the majority of cases these people "pass" without the average person being able to identity them on the street.

And my point isn't to try and claim that just because intersex people exist that the terms are useless. My point is that the definitions people try to ascribe to those terms are statistically more likely to exclude other groups of people (who the definitions are not intended to exclude) than they are to exclude trans people.

Definitions that don't work:

- Defined by "passing"/looking like what society expects a given sex to look iike: Refuted extremely commonly by queer people of all kinds. Also just wildly subjective and impractical.

- Defined by chromosomes/karyotype: Rule broken by prevalence of intersex people. Additionally from a biological perspective so much more goes into sex determination during gestation and afterwards than just the karyotype.

- Defined by presence of breasts: Indistinguishable at birth and defined by hormone levels. Rule broken by numerous medical conditions. A woman is not less of a woman for getting a masectomy or double masectomy. A man is not less of a man because medication or hormone levels cause them to grow breasts.

- Defined by the presence of primary sex organs (testes/ovaries): Rule broken by numerous medical conditions. A woman is not less of a woman for getting an oophorectomy and a man is not less of a man for getting an orchirectomy. Likewise a woman who has lived her entire life as a woman who finds out that her ovaries differentiated as testes is not any less of a woman nor the reverse for a man. And both of the aforementioned surgeries are very common.

- Defined by presence of secondary sex organs: Rule broken by numerous medical conditions. Bottom surgeries for trans people arguably make up less of the share of genitoplasties performed than the numerous other reasons (recovery from trauma or disfigurement, recovery from cancer, etc). And surgeries like hysterectomies occur in up to 20% of women depending on the region. Having or not having one or more secondary sex organs isn't a reliable differentiating factor and unless you are storing photographs of genitalia from birth and sharing them with every person or organisation that want's to know your sex then this isn't a reliable method either. It's unnecessarily complex and/or it's unnecessary exclusive.

- Defined by hormone levels: Rule broken commonly by intersex people. Commonly broken by people with various medical conditions and/or medical interventions. A woman with low estrogen levels isn't less of a woman. A woman with high testosterone (such as due to PCOS which occurs in as high as 20% of women) doesn't make a woman any less of a woman. The reverse goes for men (such as men taking testosterone suppressors or blockers for diseases like prostate cancer which occurs in around 12% of men).

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At the end of the day you only really have one appraoch and that's to just be more precise, use better terminology, and use the necessary information where it's needed.

- Government and social documents (drivers licenses, passports, ID cards, etc) should just use gender. There's no reason to use anything else and it doesn't actually benefit anyone otherwise.

- Medical records should indicate known presence/absence of organs and hormone levels. Awareness of which organs are or aren't present is only important due to care relevant to those organs and their interaction with the rest of the body. And hormone levels should be documented because the majority of medical distinctions for healthcare purposes (risks, dosage changes, interactions, effects on the body, etc) are tied to hormone levels. If someone is manually controlling or augmenting/manipulating their hormone levels that's relevant for care and it serves the patient better to be explicit about these types of things than to attempt to tie them to a single binary differentiator and make assumptions.

- Access to bathrooms, changing rooms, etc: Just let people use the bathrooms they feel most comfortable with? It's not hard, it's not complicated. If a lady or a lad is being a creep then someone can do something about it but that has nothing to do with any indicators other than "they are being a creep".

- Sports, etc: Either just divide it by gender or drop gender/sex based division entirely and divide it by skill. This is such an exceptionally small non-issue and protections against this perceived incursion have only contributed to discrimination. There is no reason why women's sports restricts competitors on their natural and/or nominal testosterone levels but men's sports do not. In competitive women's sports abnormally high natural testosterone is disqualifying but in men's sports it's a permitted competitive advantage. Additionally with regards to sports records, gendered performance differences have been rapidly closing in on a pace where they may disappear entirely within a century or less. And in particular, with non-professional sports there is absolutely zero reason for exclusionary restrictions. In those environments this is a complete and total non-issue.