“Why would the homeowners do this?”
Wild guess - they were tired of having their $hit stolen by low life scum and being told by the police there was nothing they could do about it.
If they didn’t want their stuff stolen, then don’t leave it out in the front yard.
Entrapment. And assault. These homeowners are idiots.
They were clearly driven to desperation.
Probably around 1990, in NYC, drug addicts would dig up shrubberies and other plants from homeowners’ yards, and ransom them back.
I would have figured out a way to safely plant poison ivy, myself, and tell the bums to “keep and enjoy it”.