Once and for all Dumpster Diving

Dumpster Diving Needs to have a clear answer
The scenario : dumpsters most of the time sit on private property ,Some times they sit in the street (in front of a home)
I get permission and I am so persistent that I win over individuals in charge as they see i am , safe , nice , honest . In a short time I get a wave how you do . or words of praise like better this then the land fill. In 3 years I was told no go twice and I obeyed . But am I (and we) leavening one party out, the owner of the dumpster. It seems to me they are are really at the loss . Sure the contributors of the trash can give the thumbs up for all reasons and of course a final one less weight for the purchaser of the dumpster service .
WELL do I also need permission from the Dumpster company cause when you come down to it why would a company ever say - SURE take out 2000 pounds of metal leaving behind rock ceiling tiles ECT , It's our pleasure to help out our fellow man and save people money heck thats why we have these containers to help people .I know i am being sarcastic. ONCE trash is in container on private property or street whose trash is it the original source or the container company
For obvious reasons if I get a thumbs up from the wrong person in charge like the home owner or GC - I might be in for a surprise from the container company as they MIGHT be the final word .