Also, what she said.
The bathroom issue posses the same problem. If you think the test should be identity, then yes mtf that are just starting transition will be in the bathrooms with your dds. If you think the test should be biological, that means ftms (with full beards, testosterone, and male body parts) will use the bathroom with your dds. Given there are only 2 bathrooms, there are no perfect choices here either. Just go away and don't use the public bathroom is not an acceptable outcome. Short of a massive building campaign requiring places of business to have now 3 bathrooms, I don't see how this goes away, so the question is not where we draw the line, but when in the transition do we draw the line (e.g., after SRS, after hormone treatment, after declaration).