I agree that county ordinances don't apply to incorporated cities, but I thought I covered that when I said that municipalities within the county likely have similar ordinances.
In any case, here's the ordinance for the City of Los Angeles. Interestingly, it seems to apply to any solid waste container, not just recyclables, and it also seems to prohibit placing items into someone else's cans ("tamper with...the contents thereof"):
https://codelibrary.amlegal.com/codes/los_angeles/latest/lamc/0-0-0-163740#JD_66.28.
SEC. 66.28. SOLID WASTE – TAMPERING WITH.
(Title and Section Amended by Ord. No. 182,986, Eff. 5/28/14.)
No person, other than the owner thereof, the owner’s agents or employees, or an officer or employee of this City or any person holding a contract with this City for the collection, management and/or disposal of solid waste, shall tamper with or remove any solid waste, solid waste container or the contents thereof from any location where the same had been placed by the owner thereof or the owner’s agent, whether or not such container conforms to requirements or description set forth in the rules and regulations of the Board.