Yep. I love all the perfectionists here who never make a single mistake in life, especially one as big as a typo. And because proofreading is a completely error proof process done by humans who are completely infallible 100% of the time...
Even professional proofreaders screw up. That's why they have redundancy and specific methods, and shit still happens and errors get fixed across reprints/editions. In my experience with non-professional proofreaders (i.e. letting higher-ups look through things), they skim, catch the occasional big mistake, and pass it to the next person.