I agree, people's assumptions tend to blow up or dissolve when they meet a trans person.

There was a 2018 study that literally asked a thousand people if they'd date a trans person, and 9 out of 10 said they wouldn't consider it. (It was cited in the article to which I was indirectly responding.)

https://journals.sagepub.com/doi/abs/10.1177/0265407518779139?journalCode=spra

But the thing about speculative questions like this—Would you consider dating a trans person?—is that people don't know what they'd do in unknown future situations. They're not considering dating a trans person right now because they don't actually know what a trans person is. The trans-person-who-is-attractive-to-them isn't standing there right now at the moment they're being asked about the hypothetical. If the follow-up question were And can you explain to me what kind of person you think a "trans person" is, such that you wouldn't date them? they'd give some narrow definition of "trans" that doesn't accurately encompass the diversity of all trans people. Probably there is a trans person out there who they'd consider dating when they met them.

And I guess the same point applies to a lot of gay and straight people who consider themselves to be at the far end of the Kinsey spectrum. They say they're open to dating people exclusively of one sex/gender because, >99% of the time, that is how their attraction works. But there could be an outlier over the course of their lifetime, e.g., "I would make an exception for this person." So when people say "I'm 100% gay" or "100% straight," they're saying something about their identity and how they want others to see them, e.g., they don't want to be set up on dates outside of their gender preference (because it's very unlikely to be a match, and there's no need for other people to try to force it), but that doesn't necessarily mean they're never going to meet a single individual of some other sex/gender who they're surprised and happy to find themselves interested in.