I did some asking around about your question. In this area most of the garbage contracts...residential and industrial...are awarded to companies on a bid basis. I don't know how often they bid or what they make but the same people have been doing the work ever since I can remember.
We looked into a contract for our end dumps hauling rubble from a huge demolition site to the local landfill. The tipping fee for our loads would have been five times what the normal tipping fee was. The same company that owned the landfill also did trucking and brokering.