Apparently, some self-identified transgender people want to use restrooms and locker rooms designated for the sex that they are not yet physiologically. In other words, they have not yet undergone, and perhaps do not plan ever to undergo, sex change surgery. So, to be very specific, a person with “male parts” who identifies as female wants to use the locker room designated for females….
…I do suspect the source of controversy is the idea of a person with “male parts” using a locker room designated for girls and women. (I suspect few men really care about females using restrooms or locker rooms designated for boys and men.) To be very specific: I suspect many men and women care about anyone with “male parts” using the same restroom or locker room as their daughters and granddaughters.
So let us please look at the controversy through that lens in order to clarify it.
I propose that we distinguish between gender and sex in this controversy and insist that a person use the locker room (restrooms are really less a problem because women’s have stalls) designated for the sex he or she still is—until he or she has completed sex change hormonally and surgically. Otherwise, the specter (realistic or not) of sexually male persons claiming to be women walking around naked (locker rooms have showers) in women’s locker rooms is unavoidable.