California Code, Public Utilities Code - PUC § 524

(a) Any common carrier may issue free or reduced rate passenger transportation to the proprietors and employees of newspapers and magazines and the members of their immediate families in exchange for advertising of equal or greater value in that media, subject to reasonable restrictions that the commission may impose.

(b) The San Francisco-San Jose commute rail service may issue free or reduced rate passenger transportation to the proprietors and employees of the broadcast news media in exchange for advertising of equal or greater value in those media, subject to reasonable restrictions that the commission may impose.  On or before January 1, 1989, the Department of Transportation shall review and assess the effectiveness and cost of any advertising program effectuated through exchanges made pursuant to this subdivision.

(c) Passenger stage corporations may issue free or reduced rate passenger transportation to any of their commission agents.