I don't believe I have ever seen a single example of a whitelist not being a list of exemptions. Nor can I seem to find any.

Nor can I find any example where blacklist is not a list of denied subjects. A blacklisted person, website or process is immediately clear within their context.

Where the clarity is lacking is not clear to me. However the mismatch between "allow list" and "whitelist", is. The latter seems to have a different meaning altogether.