Certificates cost approximately nothing to issue, and most of the CA's infrastructure would not need significant scaling with the issuance of more certificates.
Manual validation of human/organization identities (the type that requires reading identity documents, such as for EV) costs money, and that could have associated fees, but it doesn't need to occur on a per-certificate basis. And automatable validation costs nothing.
In particular, wildcard certificates don't need to cost any more than standard certificates, and no-cost wildcard certificates would change the SSL landscape significantly. Today, any service that uses subdomains incurs significant fees to secure those subdomains.