I tend to think it runs deeper than this though. We aren't necessarily offended by things we misunderstand. I think they feel threatened. Why else would they act with hostility?
None of the following is intended to justify how a person feels or reacts towards trans people. It's just certain things I've noticed.
I tend to notice a fair bit of the hostility is directed more towards trans women. I have my own theory that that ties into misandry. People who don't want to accept that biological men can become women and those who either dislike men or fear them, may not like them coming into spaces that were previously free of them. I think that perspective exists.
It's obviously debatable but- people who think men historically and currently have more power may see trans women as an extension of that.
I tend to notice that men who envy women focus a great deal on 'pretty privelage'. Also that some trans women are extremely stereotypically glamorous and attractive. Which of course- is their right. It's any woman's right- if she enjoys looking like that.
I suppose it still reinforces a stereotype though. One that cis women have been trying to break perhaps. So, it's effectively men becoming women and complying to the stereotypes created by men.
So- perpetuating what women 'should' be doing to appear attractive. That can be an issue if we find those things exploitative or repressive. Do we really want to wear revealing, tight fitting clothes? underwired bras, High heels? Make up? Are any of those particularly practical?
I suppose there are the more hardcore religious set that don't like either gender or sexual fluidity. Even though we are surely born a certain way so presumably- their God intended that.
Also- sexuality itself. A guy at our workplace found another guy who transitioned creepy. He was especially hostile towards her. I think possibly because in his mind- she was still a man. Maybe he was afraid that he could be lured into what (he presumably would still see) as a homosexual relationship. So, I think it can link to homophobia as well. For someone who doesn't believe a person can truly change their biological sex and who has homophobia, I think they find that side to it disturbing.
As it happens, the trans woman at our workplace was still into women anyway so- his (presumable) fears would be unfounded! It's also pretty arrogant anyway for him to assume she would find him attractive regardless.
As for the NPC label- to any of us presumably, it's the other people in our life who are the NPC's. We are playing us- at the end of the day. With our own set of perspectives, morals, ideas. For some people- they may never actually come into contact with a trans person in real life. I think maybe I've been around 2 and, I'm 45.
So- the majority of trans people they see may well be via the media. Which has (understandably) become so PC now that we get every single variety of gender, race and sexuality represented. Those people are probably actors a lot of the time so- genuine NPC's in terms of the parts they are playing. They may not in fact be trans or gay for example. So- arguably- the trans people they are aware of are in fact NPC's- literally! They are actors.
It can absolutely feel fake too. Like a deliberate decision to feel inclusive- that doesn't really quite gel. More like- the token person thrown in to try and appear PC. To effectively try and get us to be inclusive too. Which they may not appreciate- if they don't want to be.
My Dad for example isn't particularly prejudiced in real life but, he doesn't like the representation of it all on TV. I don't necessarily agree with him there. I don't think societies gel well being segregated and one way to encourage acceptance is to normalise it in media.
In terms of attitude though- I agree. They ought to acknowledge that we can be born with or develop strong feelings that we are a certain sexuality or gender- that doesn't necessarily align with our physical form.
There again- the practicalities of accomodating that- so that everyone is happy can be complicated. Effectively- one group of people feeling their righrs are being encroached upon by another's.
Ultimately- we all live life with our own specific history. Our upbringing and culture. If we happen to have parents with very strong and outspoken views say- we can pick that up too. That can be a person's reality. In a way, I think it's actually quite a feat to break away from what we've been taught for 18+ years and- think for ourselves- over everything.
Obviously, we'll make the effort if it's something that affects us directly. If we realise we are gay or trans and, our parents are very anti both- we may have to overcome all the stuff we've been taught to be comfortable in ourselves. Then, there's the risk of telling them and trying to change their ideas.
If we're cis though and, we have little to do with the trans community- will we work so hard to challenge prejudices we may have been taught? We should of course but, that goes for everything in life too. Isn't the kinder choice to be vegan but then- how many of us are? How much effort do we put into living lives that cause no harm to others? Do you feel like you've banished all prejudices you were taught?
We also have our own biases fed by our own experiences. We're human ultimately. I can't say I particularly liked this trans woman at work. She was suitably bitchy! I've also run into other trans people who will seemingly look to take offense. While I can understand that- if they've suffered a life of persecution, my own history of having people in life I needed to walk on eggshells around (not because of being trans,) I really don't want that kind of drama in my life now. I don't want to be accused of causing offense if it was never my intention. If I was simply asking a question.
I suppose I probably should have been better informed not to ask certain questions but then- that's the other thing- should we be expected to be an expert on all issues before having questions or opinions? We kind of can't- for all things. So again- I usually try to steer clear- rather than get involved. Although, I have (possibly stupidly) here again.
So- I think it's more nuanced than people simply not thinking deeply. I think we may have prejudices that- despite trying to reason away, still partially stick.