@electricdreaming said - It’s a complex argument and it’s difficult for me to articulate myself well because I simply don’t know enough about the history of transgenderism to argue why it’s left wing - I just think those in favour of better rights for trans people would view themselves as on the left.
Surely the whole trans debate shows precisely why we have to ignore how people view themselves and focus on reality?
It is perfectly possible for people's self-perception to be 100% a provably the complete opposite of the truth, so the idea that self-perception on something subjective (whether one's views are left or right wing) has any real value seems nonsensical.
To my mind the left is about fighting for the rights of the oppressed - both large oppressed groups like "ordinary people" and smaller oppressed groups like lesbians or trans people. It is about economic justice, and believers in justice often seek social justice as well.
The left includes two groups who are doing massive harm, both directly and by diluting the potential of the economic left to achieve change
(1) Good people who have not thought the T issue through.
(2) People who support queer theory, either out of naivity or a desire to destroy society.
It only appears to be a left wing issue because the left tends to be more progressive and if you don't think at all deeply the issue appears to be a progressive one.