I am trying to confirm if Reg DD governs business accounts. I have found this in my research that Reg DD governs consumers. And consumer are defined as follows:

(h) Consumer means a natural person who holds an account primarily for personal, family, or household purposes, or to whom such an account is offered. The term does not include a natural person who holds an account for another in a professional capacity.

Accordingly, it looks as if it does not govern business accounts, which ties along with Reg Z. Correct or incorrect?

Correct.

You are right. Originally there were questions on how it applied to bowling leagues and such. The "PFH" test works nicely. Many banks will choose to over-disclose and will provide these even when not necessary. In those cases, watch that you don't create contractual terms you don't want.

What is the "PFH" test?

Personal, family, or household purposes.