Why don't very many HTTPS/SSL websites supply identity information in their certs?
Ownership information requires an actual human to look at documentation submitted and verify that it's correct; you can't automate verifying a human-level concept like ownership. If a certificate needs a human to look at and manually approve it, that costs money. Since ownership information isn't something that's very visible to users except for EV certs, and most users don't care almost all of the time, there's no reason to spend the extra money for an ownership-verifying certificate.
(edit: It's not enough for the site to just put it in a cert: for ownership verification to be done in the cert, the CA has to verify the ownership themselves; no CA is willing to sign something claiming to be a person or company unless they verify that that's actually true).