I remember hearing a (possibly apocryphal) story about how it was discovered in one town that all of the recycling was getting incinerated. It was then asked why they needed to sort everything, and the answer was that it was useful to help control the temperature of the incinerator.
If the flame was too cool, throw in more plastic. Too hot, more wet compostable material.
When I was in college I did some report on our local recycling program. I interviewed a manager and learned that our recyclables were actually mixed and trucked to a town several hours away because we didn't have the volume to sell the sorted quantities. I asked why we had to sort at home then and he said "well if we ever can sell individually we want people to be used to it." I never sorted my recyclables again.
Where I live now it isn't even possible, all recyclables go in one bin.
If the flame was too cool, throw in more plastic. Too hot, more wet compostable material.