It's quite possible you're right, and I can't deny that my brain is pretty twisted anyways. That said, I feel like there's a clear difference in taste between brands, at least for my own taste buds.

I drink Coca-Cola as my preferred choice. I can't stand Pepsi (and will order a new drink in a restaurant if Pepsi shows up when I ordered Coca-Cola; I can tell, even if it's not labeled). There's a specific sweetness to each, to my tastebuds. I also enjoy RC Cola, but it's also a different flavour from either of the two most well-known brands.

I get pretty specific in my tastes, especially surrounding extra flavourings. I dislike vanilla flavouring added to my colas, though I will still drink it paired with another flavour such as orange or cherry.

I will choose Cherry Coke (classic) over just Coke any day, but will choose just Coke over Cherry-Vanilla Coke. I'm willing to drink Wild Cherry Pepsi (actually quite good), even though regular Pepsi is not a flavour I enjoy.

There's an interesting version of Pepsi called Pepsi Throwback (at least, that's what it's called around here) which I also enjoy greatly. It uses a different sweetener than regular Pepsi.

I can't stand either Diet Coke or Coke Zero (or any Diet soft drinks, really); neither taste right, to me.

Now, I still think New Coke vs Coke was overblown. I don't fault the Coca-Cola company for trying to shake things up a bit, and perhaps the new formula could have appealed better, given time and a better launch. We'll never know, though ...

> Either my qualia are objectively different from everyone else's

Yes. I mean, not everyone else's, but certainly many.

> What I find incredible is just how similar everything tastes.

Vaguely similar, maybe. Incredibly similar? That's either you ignoring or being biologically unequipped to tell the differences.

> I just find it hard to believe that the difference is so great that people can find one repulsive and the other divine.

They taste different. In some cases radically different. Cokes and Pepsis are reminiscent of each other, but the difference between them on, say, a multidimensional tartness-sweetness-bitterness spectrum is as great as the similarity between them on the cola-hotdog spectrum. It's not difficult at all for me to recognize why people might like the taste of one and not the other.

If they were actually the same, the blind "Pepsi Challenge" wouldn't have worked as well as it did.

Next you'll say that you think Heinz ketchup tastes like Hunts ketchup, something which is just logically untrue, as if the ingredients and their proportions don't matter. Are they both ketchup? Yes. Do they taste the same? No. They don't mix the same ingredients in the same proportions. When two things are different, is it reasonable to form preferences even if those preferences are sometimes circumstantial (A better on X, B better on Y)? Yes.

I don't want to downplay the mental aspect of it, but I do want to point out that sugary drinks like soda taste differently if you drink them all the time vs. only once in a while. Once you get used to the overpowering sweetness the other flavors make more of a difference.

Personally, I absolutely find non diet coke way worse than diet or zero coke due to its syrupy-ness. So I think many drinks do have very distinct tastes (though many are also similar).

I could tell the difference easily. New Coke tasted just like Pepsi, and Pepsi is too sweet. I can drink a whole Coke and feel refreshed, but if I do that with Pepsi I feel slightly queasy. It's like chugging maple syrup. In a blind taste test sweeter always wins, but less sweet is preferable to me (and apparently to a lot of people) in a full serving.

I find incredible how similar zero sugar coke is similar to regular coke.

Even a small difference in taste is enough for people to prefer A over B for the rest of their lives. The products don’t change. That’s worth billions.