We don't add page numbers because they would be different on different editions of the same book. Different editions in formats such as hardcover, paperback, anniversary editions, etc. all have identical recipes but different layouts so the page numbers are different in each. We index one edition and then link all the others so the recipes show up regardless of which edition you own. If we put in the page numbers for the edition we indexed they would be wrong for the other editions.
We may be able to work out a way that members could add their own page numbers to recipes for the edition they own, which would then be shared with other members. We will post this on the EYB Blog if we find a way to do this.