I don’t have a definitive answer, but I can offer a couple of observations: 1) It would add to the cost of trash pickup. You’d need to add either a second route or an extra bin to the truck. In my area this latter is sometimes done; you see garbage trucks cruising around with a dumpster on the forks while also doing curbside pickup with the lifting thing on the side. 2) it’s probably best to do composting in a decentralized way. Rather than toting all the compostable matter to a central location and then shipping it off to where it is used, it might work better for a group of people in a neighborhood to pool their compostables for use by local gardeners. 3) Not all decomposable materials are suitable for compost, and not all garbage-collection customers know what’s what. If you mix dirty or non-recyclable materials in with the recycling, it costs more to process it but the unsuitable stuff can be sorted out. If compost becomes “tainted”, it’s a lot harder to separate out the bad parts, and it’s impossible after mixing.