I think you have slightly missed the point: it isn't just that people are charging for making available a public domain work: nothing wrong with that - and you would be free to make your own copies and pass them on (because it is public domain).
Rather it is that by "republishing" in this way they can claim copyright in the new version and can then not only charge for selling them but can also restrict your rights to pass it on. A bit like someone deciding they can remove the GPL license simply because they are publishing the software on a new medium. The point being that GPL software *is* protected by copyright whereas (by definition) public domain works aren't.
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