So, Verisign is an interesting example.
Verisign sold their certificate business a long time ago to Symantec.
Symantec had a contract with a Korean company "CrossCert" in which Symantec would issue certificates (including "Verisign" certificates) based on CrossCert's validation.
We don't actually know what CrossCert's validation practices were, because during investigation of problematic certificates Symantec found that CrossCert wouldn't give them the paperwork they should have been keeping to track this work so that it could see what they'd done. It had never asked to see that paperwork previously (over years of the relationship) and had simply accepted a Korean auditor's finding that everything was fine without really inspecting anything itself or letting anybody know about this arrangement with CrossCert.
Did you know about? When you see "Verisign" do you think "Or, you know, maybe some Korean company, but that's fine?"
Never mind, this scandal eventually resulted in Symantec exiting the CA business late in 2017, and today "Verisign" certificates are issued by DigiCert, another company you've probably never heard of.