I'm honestly curious why that's the case.
Because they can get away with it. In the PMC circles were transphobia is rampant, you can't be nearly as mask-off about hating other minorities because they have put decades of political, social and legal struggle into fighting at least some of their marginalization. We have as well, but in smaller numbers and usually under wider umbrellas liek the LGBT community in general. Under capitalism, the issues of these less villified minorities are ofc never fully redressed, but liberals have grudgingly enshrined at least some cost-neutral concessions to them into law, MSM at least feigns to be on their side against bigottry, and that doesn't apply to us in the same way. We're so few, we've had so little opportunity to make ourselves heard until recently. Most people have no clue about how we live and what we have to put up with, the constant hostile stares, the chasers that let go of any decency they'd feign towards a cis woman as soon as they learn we're trans, the segregated medical system that makes the battle against our non-compliant body as hard and slow as possible, the government-mandated deadnaming, the need to train yourself to avoid comment sections if you want to sleep tonight. The masses are blissfully oblivious to that. Even most allies have no idea how deep our ostracism goes. We are literally kept second class human beings and the PMC shitstains love that, it gives them a sanctioned outlet for all the other bigottries they have to keep bottled up. They don't just hate us, ofc somebody like JKR also hates jews and asians and black people and gays, but she can't say that aloud. But she can say aloud that she thinks we're all mentally ill predators, because nobody gives a single fuck about our dignity.
Because liberals don't defend them, I guess? They were perfectly happy using the n-word and "Segregation now, segregation forever!" until culture moved away from them.
Personally, I think it's more that it's still acceptable to be explicitly against trans people, much like how other groups, throughout history, have received a similar treatment.
There's a lot of factors tbh but I think one is that conservatives hate science. They've hated it ever since it said that evolution is real, and most US conservatives continue to deny that evolution is real. They see science as something that is fundamentally opposed to their religious identities, and which is constantly trying to expand into areas where it "doesn't belong," (outside of "hard" sciences). Of course it's not limited to evolution, but generally there's a large, influential section of conservatives who want to discredit science in general (polls generally show around 30-40% of Americans are just straight up evolution deniers), in hopes of winning that age old culture war, and of course the whackjobs' interests are aligned with money that wants to pretend climate change isn't real.
The science is all very clear on trans people existing, the efficacy of hormone therapy, and the importance of social acceptance and support. But you have this population that is primed to distrust science and is actively looking to discredit it, especially when it introduces them to something outside of their experience and asks them to change their behavior. The same factor is also observable in the anti-mask, anti-vaccine sentiment. It wasn't just that people didn't want to wear masks, it was also that they wanted to make the case that science was being unreasonable and stepping out of its lane.
I singled out evolution because its a very classic and influencial example, but while it's arguably the father of the movement, "Hate on trans people to discredit science so people come back to church" is only one part of that anti-science movement which is in turn only one part of transphobia. There's also a whole ecosystem of grifters selling fake medicine and such, and people just in it for the clout, and people who buy into the anti-intellectualism but become doomers about it like the "eat bugs and live in a pod" types.
Like I said I think there's a lot of factors and that's not necessarily the biggest one but it's an angle I don't see talked about much so that's my contribution.
I have a mild thought that pushing anti-science is a way of having a ready population of people that will respond viscerally to any infringement of property rights. The propertied class will periodically butt up against something that the scientific community will say is damaging. Having people already primed to hate science is very useful for reigning in any regulations.
Modern version of how the anti-religious sentiment in the founding fathers was partly because religion was one of the bulwarks against what could be done with slaves.
All good observations here already
The only thing I’ll add is that being trans is the perfect nexus of three of Americas favorite pass times:
Misogyny, patriarchy, and homophobia
