#probably already something about this in canon thst confirms or shoots down this thought I missed

[brotoman-exe]

Random Bionicle Thoughts:

That beings in the Matoran Universe have essentially a geas placed upon them to not realize they are living inside a giant robot or living inside anything really. So like while the Toa Metru could notice all the weirdness about the Island of Mata Nui, like the red star and the strange organic fish the geas prevents them from truly confronting the fact that Metru Nui might be inside something. Like even Makuta Teridax had to be told about it by another Makuta who was told about it by Trem Krom and then only one of them didn't go mad from the knowledge. Even if you were there before the robot took off or the Mata Nui AI was installed, like Karzahni, it seems there is a distinct issue actually understanding what you were and where you were before the awakening to sentience.

Which while the awakening of sentience in beings like Matoran and Toa was never intended, the GSR did seem meant for testing artificial environments so something to passively keep those created beings from figuring it out would be a bit of a failsafe.

Also imagine after Spherus is reformed there is a bit of a massive psychic release as all of the Matoran Universe learns the truth. It probably takes some time for many to really adjust to that reality.