I had an odd experience taking styrofoam to the dump in SF. On most days I would be told to just put it in some random dumpster, no receipt written up and no ve

I had an odd experience taking styrofoam to the dump in SF. On most days I would be told to just put it in some random dumpster, no receipt written up and no vehicle weigh in/out or anything. I figured that was just the process until one day I was told to take it to a specific place where there was other styrofoam being collected, my vehicle was weighed in/out and a receipt generated. Who knows what they were doing with it on those other days?