I think you are right about the text you quoted. That said, it is a digest of the law. The actual law is:

(d) A rental company may charge a fee for an authorized driver, in addition to the rental charge for an individual renter, unless the authorized driver is either of the following:
(1) The renter’s spouse, as described in paragraph (2) of subdivision (e) of Section 1939.01, the renter’s child or person for whom the renter is a legal guardian, the renter’s sibling, or the renter’s parent or grandparent.
(2) The renter’s employer or coworker, as described in paragraph (3) of subdivision (e) of Section 1939.01.

The one who drafts the Digest appeared to have inadvertently dropped the "the renter's" and thus totally skewed the meaning. Interestingly, it seems that one can add their grandparents for free, but not the other way around.

Ref (including both the digest and the law): page 5 of the PDF.

On a related note, I chat with Hertz representatives through text message a few weeks ago. They were not familiar with the CA situation, but after I quoted the law, they said that I were right and my parents could be added with no additional fees.

I hope the reason they agreed was that they did their research (like talked to someone in a CA office), not just to brush me off. My trip is in 2 weeks, so let's see.

Avis says "In California, additional driver fees do not apply to a parent, sibling or child of the renter" on their website, so I booked one as a backup.

Hope these helps.
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