Reading Amazon Kindle books whose written language is English, I feel there are quite a few typos. It might be my misperception ... but if it was really so, why are there this many typos and why are these left as they are?

I don't know whether there are a way to update those files to correct those typos. I wonder in what way those Kindle books are edited and fabricated. Do paper books of the same titles contain as many typos as Kindle version?

Writing this, now I realize that I don't know how much typo rate is normal for a book.

By the way, this blog is very, very, very rich in typos. Ah, what a double standard I'm showing here!

But it must be required to cultivate the ability of swiftly detecting typos the kind of which spellchecker don't detect. To give one example: "than" and "then". Even a stealthy variation in a single letter in a word can badly mess up the intelligibility of a sentence.

A more advanced typos-detection ability would indicate more advanced English skills.

Considering this way, encountering typos in reading exercise might not be all bad.