California Code, Vehicle Code - VEH § 26712

(a) Every passenger vehicle used or maintained for the transportation of persons for hire, compensation, or profit shall be equipped with a defrosting device that is adequate to remove snow, ice, frost, fog, or internal moisture from the windshield.

(b) This section does not apply to an autonomous vehicle, as defined in Section 38750, that is not capable of operation by a human driver seated in the vehicle, provided that this exemption is consistent with, or authorized by, any applicable federal law, regulation, or exemption thereto.