I'll start off by saying that I take the word "phobia" is a loaded gun, used as a political tool and popular because of its insidious claim but perhaps not a word a serious philosopher should be using. Phobia is a philosophical/political interpretation of a lot of things but prejudice is a big one, I think in examples like transphobia and Islamophobia prejudice against these groups would for many be sufficient to make a claim of transphobia or Islamophobia by itself. Using that interpretation it's self-evident that prejudice is a phobia but if you actually think there's some real truth to this, I don't know what to say, that's a bad sign.
There are all kinds of prejudices, thinking they're all irrational fear lacks any kind of nuance and I don't think it's even a truth claim, I assume there's some other kind of motivation at play (like a political or interpretative one).
So, I would prejudice against someone with a rat tail, mohawk or goth attire without any negative feelings towards them, it just seems obvious to me that a person with that kind of attire lives a certain kind of way. I would assume they don't have a great job, that they aren't that articulate, that they don't go to fancy restaurants and a whole plethora of other things. Most of those things, there's not that many possibilities for someone who looks like that to have a successful job, as either a business owner or employee, only a few kinds of jobs would allow for it and they're not that well paying. If they are, they're not necessarily good jobs that put them high on any social hierarchy. Now I'll give the individual chances to prove me wrong but my assumptions aren't positive but there's certainly no irrational fear lol.
People also make positive assumptions, one that I see a lot is assuming good looking people are above average intelligence, have good paying jobs, they're popular and they get high-quality girls/guys very easily. The opposite is true for unattractive people, it's clearly got nothing to with fear.
In fact, I prejudice against people on this forum, I don't need much, I see a really stupid name and it's already a bad first impression. What about Wallows, thread names? As soon as I saw them, I'm not scared of wallows, let me assure you of that but of course, I start making all kinds of assumptions about who in their right mind could make those threads - if we even generously assume he's in his right mind at all.
Do you actually have some kind of argument? Or do you just more so wish it were the case that it was so?