While they refer to the same book they are not the same editions of this book. Some are hardcover, some are paperback, some are later editions and only some of them are actual duplicates of the same book (just have a look at the different ISBNs).

Sharing the reviews between these different editions might seem logical for some cases, but a reader might also review the actual quality of a specific edition (poor print quality, cheap paper, etc.). Even the contents of books (mostly in scientific literature) may be vastly different between two editions. So sharing the reviews is a dangerous thing to do.

So in your case this is not due to a lack of federation but because these are actually different books and in a few cases duplicates of the same book (someone didn’t check if the book existed in the first place or was unhappy on how it was represented).