I think there's a very distinct difference in how American and British culture views self-determination and personal autonomy. American culture seems to me broadly predisposed to take self-determination seriously, and regard it positively: it's seen as a virtue to assert one's sense of self, and individuals are seen as the best authority on themselves. And that (with the exception perhaps of conservative Christian Evangelical communities) is pretty true regardless of politics. So (non-Evangelical) American conservatives might see trans people as weird, freaky and undesirable, but they don't basically doubt that we're telling the truth about our experience of transness.
British culture tends to see such self-assertion as attention-seeking and spurious: the ultimate authority on your identity is other people. You are only anything insofar as other people can be persuaded to assert it; self-assertion is mistrusted - if you have to state something about yourself, it can't in fact be true. And this is also broadly true regardless of politics - as common among people who would call themselves left-wing as right-wing. Acceptance of gay people tends still to be conditional on a certain sort of empirical cisnormativity; bisexuality is widely distrusted (attention-seeking), and queer identities that don't fit a cis norm are even more suspect (worst of sins: thinking you are special). So where socially liberal Americans tend to accept a very broad range of queer identity, a lot of Brits have this sceptical-empirical thing going on. (There's a big overlap between militant atheism and transphobia in Britain too: the source of this puzzling assertion that being trans is a "religion" that we're imposing on others.)
I would also add that there's a certain sort of British person who identifies as "left" but is unthinkingly imperialist and Unionist: among English transphobes reflexive Unionism is almost universal (transphobia in Scottish Nationalism is its own fascinating subject) and those attitudes are also reproduced widely on the right wing of the Labour party and in the UK Guardian/Observer editorial.
no subject
British culture tends to see such self-assertion as attention-seeking and spurious: the ultimate authority on your identity is other people. You are only anything insofar as other people can be persuaded to assert it; self-assertion is mistrusted - if you have to state something about yourself, it can't in fact be true. And this is also broadly true regardless of politics - as common among people who would call themselves left-wing as right-wing. Acceptance of gay people tends still to be conditional on a certain sort of empirical cisnormativity; bisexuality is widely distrusted (attention-seeking), and queer identities that don't fit a cis norm are even more suspect (worst of sins: thinking you are special). So where socially liberal Americans tend to accept a very broad range of queer identity, a lot of Brits have this sceptical-empirical thing going on. (There's a big overlap between militant atheism and transphobia in Britain too: the source of this puzzling assertion that being trans is a "religion" that we're imposing on others.)
I would also add that there's a certain sort of British person who identifies as "left" but is unthinkingly imperialist and Unionist: among English transphobes reflexive Unionism is almost universal (transphobia in Scottish Nationalism is its own fascinating subject) and those attitudes are also reproduced widely on the right wing of the Labour party and in the UK Guardian/Observer editorial.