I'm afraid I still don't fully understand the point of your post. I honestly don't find this illusion bizarre any more because I do understand what our visual system is reporting. You ended the post with what sounds like a request for an explanation that renders this illusion non-bizarre. I think between the various responses that has been provided. You seemed resistant to accepting that explanation initially which is probably why discussion of it took over the comments.
It is true that most illusions have an explanation that renders them non-bizarre. This one does and it has been provided. What other point(s) were you hoping to make?
You ended the post with what sounds like a request for an explanation that renders this illusion non-bizarre.
This was my miscommunication. I was skipping over the explanation in an attempt to cut on length.
You seemed resistant to accepting that explanation initially which is probably why discussion of it took over the comments.
I was trying to avoid talking about the explanation because in my mind the post was only using that particular example as an example. I was perceiving the ensuing discussion as nitpicking. (And fully acknowledge that this was ...
Today I looked at the above illusion and thought, "Why do I keep thinking A and B are different colors? Obviously, something is wrong with how I am thinking about colors." I am being stupid when my I look at this illusion and I interpret the data in such a way to determine distinct colors. My expectations of reality and the information being transmitted and received are not lining up. If they were, the illusion wouldn't be an illusion.
The number 2 is prime; the number 6 is not. What about the number 1? Prime is defined as a natural number with exactly two divisors. 1 is an illusionary prime if you use a poor definition such as, "Prime is a number that is only divisible by itself and 1." Building on these bad assumptions could result in all sorts of weird results much like dividing by 0 can make it look like 2 = 1. What a tricky illusion!
An optical illusion is only bizarre if you are making a bad assumption about how your visual system is supposed to be working. It is a flaw in the Map, not the Territory. I should stop thinking that the visual system is reporting RGB style colors. It isn't. And, now that I know this, I am suddenly curious about what it is reporting. I have dropped a bad belief and am looking for a replacement. In this case, my visual system is distinguishing between something else entirely. Now that I have the right answer, this optical illusion should become as uninteresting as questioning whether 1 is prime. It should stop being weird, bizarre, and incredible. It merely highlights an obvious reality.
Addendum: This post was edited to fix a few problems and errors. If you are at all interested in more details behind the illusion presented here, there are a handful of excellent comments below.