For well-established journals, the editorial board finds new editors, so there is no cost involved for publishers. With respect to typesetting and proofreading

For well-established journals, the editorial board finds new editors, so there is no cost involved for publishers. With respect to typesetting and proofreading, my personal experience is that the 'service' provided by Elsevier was of such a low quality that it actually caused _increased_ effort on the author's side. Making the articles available is indeed the core business of a publisher. However, prices for that kind of service should have decreased significantly over the last two decades, not increased.