No, I'm sorry but that is loving ridiculous. You can't use the bathroom of the opposite love just because you don't think you're supposed to have a dong or whatever. How can anyone seriously think that it's okay to go into the girls bathroom if they're biologically male just because they feel that they were supposed to be a female? If you have a snake you piss with the guys, if you have a vagina you piss with the girls and if you don't like it then you get an operation or deal with it.
I honestly can't get over how incredibly ridiculous the mere concept of such a thing is
But what if you identify so completely with the opposite gender it becomes impractical to enter the other restroom.
If a transgender individual who was biologically female but socio-psychologically male and appears to be male, the ladies in the womans room that the individual is forced to enter will now feel uncomfortable that there is a "man" amongst them, and visaversa.
I think its rediculous that there has to be legislation about this yes, but your above opinion coupled with that I can so easily bring up a counter argument shows why its needed. There is obviously a line according to most people, and the goal of the law is to try and get as aligned with the people's perception of the line, which this obviously is a very tricky subject.