Below average observer
A young woman with long brown hair put on a long blonde wig, told me she was about to, and I wouldn't have recognised her. I'd only known her a couple of weeks but still, I assumed such a simple and announced deception wouldn't have confused me.
I had chatted for half an hour with a guy who I was then told was an actor, and he was prodded to 'do his thing', and he went into character. Again, I wouldn't have recognised him unless it had been announced.
I was walking with a friend and he said, "Wow, that was cold!"
I asked what was cold. "You just walked past your mum without saying hello."
I never noticed her. In my defence she hadn't noticed me, which explains where I get it from.
He wasn't such a great observer either, he paid too much focus on faces and not enough attention on environment. One time we were walking and a woman fell down hard on the pavement in front of us and he stepped over her and kept talking. He was aware of her as a walking obstacle just not as a person.
It also fails in reverse. I passed my worst enemy in a northern town neither of us had been to, clocked him, and thought nah, my mind is playing tricks. It was him.
I am the Dunning Kruger of observation so I don't trust my observations and verify three times.
TL/DR - You may feel superior but this is a serious problem for the bulk of society. Most of us are more easily fooled than we think we can be.