The question goes to, how do you prove or meet any kind of burden of proof needed for discovery

You need a whistleblower from HR, or a person who used to work in an HR department.

I think the big problem is that this would bite all companies in the butt, including law companies. They are disincentivized to even try going after this.

Certificates or education level are also not a protected class.

Degrees and certificates are disproportionately distributed among protected classes. And the Griggs ruling is more general than protected class in general.

I, too, am not a lawyer.