Why are authors allowing this? Whenever I've been published, I've asked to retain copyright and that has been granted -- I'm not sure it's a grant, though, sin

Why are authors allowing this? Whenever I've been published, I've asked to retain copyright and that has been granted -- I'm not sure it's a grant, though, since it's mine to start with. The usual negotiating starting point is a contact from a publisher that automatically claims copyright. I simply delete that clause (and possibly insert "The author retains copyright", so that there's no doubt). Clearly, that's not happening here and I don't understand why, unless publishers are refusing to publish without being given copyright. In which case, alarm bells should be ringing very loudly.