https://www.techdirt.com/articles/20210619/12311147021/iowas-top-court-says-cops-cant-search-peoples-garbage-without-warrant.shtml

Pretty much everywhere in the United States it's accepted that if the public has access, law enforcement has access. This is the legal theory behind things like automatic license plate readers (anyone can see a license plate), utility pole-mounted cameras (anyone can see someone's front yard), and (to our benefit) recordings of public officials (if they're performing their public duties).

This theory (along with the theory of abandonment) tends to govern people's trash. Once it is outside the house and made accessible to sanitation services, it can be accessed by anyone, including law enforcement officers. Sifting through trash that has been "abandoned" is one of several ways officers compile the probable cause for search warrants.