There are policies in place as to what constitutes a trans athlete and what does not. In order for a person who was male at birth to be eligible to play for a women's team as a trans athlete, a male would have to complete one calendar year of testosterone suppression treatment for gender transition. I believe this is the same thing that is in place for the olympics?I do not know. How many would be willing to say they are female for a $250,000 worth of scholarships and entrance in a school they could not attend otherwise.
I think some people believe you can just identify as a woman and be good to go. 99.9999999% of people who do this are committed to transitioning to a different gender, and not doing it so they get a competitive advantage in sports.