If you know anything about competitive swimming, you know the time you put in at the pool is outrageous. The real swimmers are at the pool around 5:00 a.m. really digging deep for a few hours. Now why would a female athlete want to put her heart and soul into a sport, only to have a man (yes, he's still a biological male), easily beat her. I can guarantee you I wouldn't play in a sport where I was handicapped from the beginning. If I give everything I've got, I hope to win or at least place. Why compete when you know you can't win? By the way, women who transition to male and play in male sports, are having just the opposite experience, they are getting beaten terribly. The issue is male to female.
If you play competitive sports, you usually have to show your birth certificate at the very least for age restrictions. How about we take the gender listed on the birth certificate to determine which league the individual should be in? That certainly isn't a hassle. No additional people would be necessary to review the birth certificates beyond the normal process, so there should be no confidentiality issues.
Meet the beautiful Lia Thomas, swimmer extraordinaire...