Just want to clarify some things:
JSWolf: Many authors don't have the final, edited version of their manuscript in a word processing file. They might have proofs (electronic or otherwise) where they last made their corrections. Few, if any, actually input their corrections into their *insert favored word processor file here*.
If you're a publisher (or anthology editor, in the case of short stories) looking to reprint a book, the best alternative really is to OCR the document and check for scanning errors.
Anemik Oak: They might have availed of Kobo's conversion service.
Avantman: Another problem of Big Publishers when checking their books is the sheer quantity they release. And then they'll have to do it for every store. Hence they depend on the conversion company to do the actual proofing, pre-submission to the various retailers (after it's submitted to the retailers, that's out of the conversion company's hands). However, you get what you pay for: some conversion companies actually proof their documents, others don't (and some mishaps are due to the retailer, as Anamardoll pointed out).
Anamardoll: what genre do you write in? If it's science fiction/fantasy, you can try submitting to
Wizard's Tower Books and
Weightless Books. You can submit the file you want.