I've never published an edition of a public domain work, but my understanding is that someone COULD use a Penguin or other publisher's edition, which presumably is word-for-word from some other source (which in a publisher's case might be old production files from a previous edition). But the source could also be Project Gutenberg or some other public domain resource. And it could, if you went to the trouble, be an old edition, which you scanned and OCRed. But I don't think you have to go to that trouble.
What you could not use from a Penguin edition would be the original material that they added, if any, such as an introduction or scholarly notes. Those are new and copyrighted by Penguin, and that's one reason that publishers often add material to a republication of a classic. They want to give people reasons to buy it.
But the public domain material is truly free to all--to copy, to alter, to mess around with, whether we or the author or their estate like it or not.
I do think that movie adaptations are a different kind of thing, especially when the copyright is still held by the author or their estate. LOTR, for example, is not public domain, and in fact the movies would have been licensed by the Tolkien estate, with or without the right for them to review what the production company was up to (I'm guessing without, though).