Now imagine the cops in that comic have an unlimited amount of post-its which catalog the most minute and esoteric details about the faces of everyone in their city.

Also imagine that the cops have the ability to sift through and read those post-its at mechanical speeds.

Also, instead of cops they are Wal-Mart greeters.

Then you get closer to reality than the comic did regarding the topic of computer vision.

I hope you aren't implying a comic strip glossed over some details in an effort to reduce the message to a small, easily consumed and memorably sequence of events, just so they could fit within the limits of the form. I hold the medium in far to high a regard to consider that a possibility! ;)

Joking aside, I think you were primed to interpret the comic in a specific way which may not have been the intent. I don't think it was saying much about the state of surveillance using computer vision as much as it was showing the absurdity, at this point, of using a method that prevents computer vision from working but also makes you uniquely and easily identifiable. Eventually, if enough of the populace takes up a similar method of obfuscating their identity, then it's useful, as you are again anonymized as one among many, but until then you are an anonymous member of a very small group (possibly containing only you), which itself isn't very hard to identify. Not all that useful.