When people say "Trans Rights Are Human Rights", what they mean is that our fight is your fight too.
Shall people have bodily autonomy or not?
Shall healthcare be a human right or not?
Shall people have equal rights and opportunities regardless of their gender or not?
If trans people can't have rights, no one has rights, not really. They'll start with us, but it won't end there.
@malcircuit While I agree that developing just rights for trans people would improve society I do not think that trans people themselves are the vanguard of a better society.
Trans people are a minority who have initiated a fight to obtain better recognition in society and more equitable rights. I believe that when these rights will be obtained, most of these people will have no more reason to fight and will thus stop doing so.
I believe it's easy to explain why many trans are socialist or anarchist: in a political landscape where conservatives and most of the right wings is against their requests it's quite natural to turn to what's opposite to that; that would be progressive ideologies, which most left parties include, some branches of communism and definitely anarchy.
I do not think that trans rights will result automatically in other rights.