Without the legal definition, then a trans man is just as able to go into the men's restroom as the cis man.
Does there need to be a "legal definition" of what is a tree vs what is boulder? Or hasn't mankind pretty much been able to observe NATURE, and even before we had a written language, mankind was capable of knowing the differences in things by their NATURAL physical and observable traits?
Legal definition exist to prevent any ambiguity in word usage, especially in a language where idiom and slang are common and have a tendency to become part of the structured language.
So, do you need a legal definition before you call the fire department and say there is a brush fire by the large oak tree on my street--- or the large boulder if that may be the case?
Common usage of terms and definitions exist because they ARE COMMON. Same way it is common that men and women have differences which are observable, knowable, and vary slightly in function on only in nature.
For example, incest itself is only sex between blood related people, but in most laws, legal definitions exist to make it also sex between people who share a legal relationship, such as adoption or step whatever, and also often add marriage into the definition. Legal definition does not automatically equal actual definition. For that matter, a law could easily be made that states, "for the purpose of law, man shall mean any individual who identifies as a man, including, but not limited to cis man or trans man".
You are going "the long way around the block" as they say, in order to attempt justify your skewed logic on something that is already very simple to figure out. Laws regarding incest have historically been based on a NATURAL aversion to sexual relationships with close family members (siblings, parents/children)--- and for good reasons; both biologically (nature), and societal (to protect children and encourge healthy family units within the culture). That higher reasoning part of us humans which sets us apart from animals.
I'm not the one here incapable of observing NATURE
Again, how are you determining whether a person entering into the women's restroom has an XX pair or an XY pair? How is an officer of the law to determine such? Or do you plan to just suffer a lot of false arrests?
"Determining" the difference between man and women isn't that difficult when MEN AND WOMEN know the difference between what is a man and what is a woman, without some convoluted legalieeze pseudo psycho-babble sliding scale where each person is allowed to apply their own definitions--- or no definition. So, when a NORMAL person (not a loon) needs to take a piss, they go into the public restroom which is indicated for their gender/sex, which is NORMALLY not something anyone would need to overthink.
Are we talking jail time? Fines? Community service? What's your enforcement here?
Scorn and ridicule are both free, it starts there. It starts by NOT encouraging mentally ill and/or delusional people any justification for their insanity. I don't care if hurts their feelings, you tell that guy who thinks he is a female HE ISN'T and NEVER will be. You don't give lunacy equal standing. That is how you enforce it; doesn't need jail time or fines. You use the same mechanisims which societies have always used to deter abnormal behavior which short of being harmful or violent to others, does not benefit the society. Same way incest was discouraged before there were written laws and punishments attached to that kind of behavior. You looked at the person in disgust.... YUK!!!! And then if necessary you shunned or marginalized the crazy or destructive behavior. Eventualy then everyone is society gets the idea. But what you don't do is encourage or celebrate it.
Why is say NO so hard to do?
And yet you can't provide them. I mean if the problem is more than you can handle, just say so. It seems that way since you can't follow instructions.
I'm not the one here who is incapable of observing NATURE. Sorry if my frank commentary is so unsettling to you. If you don't want truth, then keep looking for those "legal definitions" which not required to be natural definitions.