Besides, the AI doesn't "think" about manipulating, it just does what it's programming/training tells it to do, no ?
Not even that, it is a statistical model based on it's dataset. If the dataset happens to contain mostly "visual impairment" as a reason for needing help to bypassing captchas (not really unexpected, because the dataset is actual text written by humans), and thus that's the most likely route it takes. GPT indeed has no notion of concepts like a goal and using deception.