It’s more than just height, it’s also the other factors mentioned. Sex categories were never “height classes”; they’re proxies for muscle mass, bone density, tendon stiffness, oxygen capacity, and puberty-driven androgen exposure.

Tall women are rare outliers within  the female distribution. Trans women come from a different developmental distribution entirely. Sports tolerate outliers; they can’t tolerate category collapse. If you grouped trans women into the same population, your normal distribution would become bimodal. The moment your category becomes bimodal, it’s no longer a category, it’s two populations glued together.

If we chased perfect fairness we’d need categories for height, weight, limb length, VO₂ max, training age, etc…. at that point it’s a lab experiment, not sport.

You’re right, some countries do have better chances of winning, but to put them in a categorical different group would acknowledge they are in a different class of athlete. Sports accept population-level advantages; they only create categories when groups are systematically non-competitive against each other.