By whom? For free? Of course not. Sold to whom? Why don’t the people who buy it from the people who gather it up just gather it up themselves, and cut out the middleman? See where I’m going with that?
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because they are obviously making enough of a profit.
No, that’s not profit - they are stealing or skimming.
We live in a carbon based world. Oil, e.g. gasoline and diesel. Pretty colored garbage cans in red and green and yellow, dutifully parsing our waste while trucks drive around and pick it up under various regulations - and fines for putting the cans out two hours before the prescribed hour - that is all statist bullshit and is only possible, if not sane or practical, under a surplus wealth society.
The short answer is, we’re broke and can’t afford such nonsense.
In scientific terms, it’s a net energy deficit.
In business terms, it’s not profitable.