When you throw
something out, when does ownership of it pass from you?
When you drop it in the trashcan? When you empty the trash into a
dustbin? When the collectors pick up the dustbin's contents? When
it's dumped into landfill (or whatever)? Never?
It probably varies according to location. In the UK, ownership of trash
passes to the local council when you put the trash in a designated bin,
box or bag on the street for collection.
My understanding is that, in most jurisdictions in the USA, trash is
"abandoned property" when you bring it to the curb, even in a
designated trash container owned by your trash hauler. This is
the result of court decisions allowing police authorities to search
the trash without bothering to obtain a warrant.
That seems to be the general take in the US. There have been instances of dumpster divers
prosecuted, but it's for trespass.