If humans sort their own trash by hand it's inefficient but the labor is "free" (opportunity cost, sure, but nobody's paying wages for the time expended). If hu

If humans sort their own trash by hand it's inefficient but the labor is "free" (opportunity cost, sure, but nobody's paying wages for the time expended). If humans sort at a central location it's far more expensive for the waste handling organization, even if professional full time sorters are far more efficient, because professional sorters need to be paid and need to be compensated if they're injured on the job. If segregated bins are ultimately dumped into one big mixed waste stream, it's stupid cargo culting to have people separate things. But that's not how I have seen it work in the cities I have lived in. Some centralized checking/sorting before processing is still required even if people are supposed to separate their own, but much less than if you just give people one giant bin to hold everything they want to get rid of. If you had a centralized waste sorting machine that could separate as well as human labor, but was much cheaper, that would be even better. (Though it wouldn't completely remove the need for household level separation: some perfectly recyclable clean paper becomes un-recyclable if people indiscriminately mingle it with food scraps or other dirty things before collection.)