Why do some people seriously FREAK OUT about typos?

It's all about standards. Once you accept errors as unimportant the standard drops. Too many people avoid using the shift key where there should be capital letters. That's pure laziness. It comes from texting where a whole new vocabulary exists. It may be acceptable on a cell phone but never in a piece of writing. Then there's punctuation. If a comma is put in the wrong place it completely alters the meaning of a sentence. For instance: "Call me John." "Call me, John." In the first instance the person is asking to be called by his name, in the second the speaker is asking John to call him and the only way to know is the positioning of the comma. That's why proper punctuation is so important.Once these things are let slip writing becomes incomprehensible.