That's complex? Maybe to someone that doesn't understand basic science. Do you fit into that category?
Using biological markers would give a binary answer every time. Most athletes in the build up to races/events are swab tested, or tested in some capacity to confirm if they've taken any PEDs. That same info would give the answer whether they're biologically male of female. Again, nothing complex there.
Because of self-identification in the last decade, this has muddied the waters because we'll have biologically male athletes, who identify as female, wanting to compete in female only sporting events. Again,
there was no complexity / issues in the previous decades/centuries up to that point. (Yes, intersex, etc cases like Caster Semenya did / do exist, but these were exceptions).