I’ve wondered about this as well, especially because in academic research I’ve needed to look at ISO standards and I wasn’t going to pay for them. I found this information given by ANSI: https://ansi.org/help/charge_standards.aspx. It seems it is really just about the costs associated for the organizations to write, administer, and supply the standards. It may be worthwhile if document databases offer access to such standards through the subscriptions that companies pay for regularly. Another possibility is for the standard organizations to offer subscriptions that allow access to all documents. It might make things more cost effective for companies while still allowing the organizations to function.