THE PACKAGES TRICKLE in all afternoon, piling up on porches across America. Big brown trucks jockey for curb space with the postal service, while gig economy drivers unload towers of boxes from generic Econoline vans. Padded envelopes might have books in them, or batteries, or USB cables. Colorful plastic pouches conceal sweaters, T-shirts, or underwear. Cardboard cartons may hold toys, electronics, or all the ingredients for tonight’s dinner. In 2018, online shopping, which now accounts for more than 14 percent of goods purchased, grew more than three times faster than US retail as a whole, according to US Department of Commerce statistics. That translates to more mail: Between 2008 and 2016, the number of packages sent by the US Postal Service alone shot up 58 percent. Each may mean one less trip to a physical store — time savings that can make an enormous difference in a busy modern life. But on garbage day, the darker side of this convenience is clear. Recycling carts overflow with cardboard — more, lately, than the market for recyclables can bear. Meanwhile, plastic bags, Styrofoam and rolls of deflated air packets (often recyclable in theory, but rarely at curbside) are bu...