As a Swiss guy, I must say I only see this in rural areas. It wouldn't work in big cities like Geneva I think (too many people living in urban areas who don't respect our wonderful country and that's a shame).
This is actually fairly common in rural areas in America too. Maybe someone sets up a bunch of pumpkins, apples, etc at the end of their driveway (which in rural America can be measured in KM) and a box to put money in.
Even the article mentions it's widespread: "Unmanned stalls with vegetables can be found all over the world. Germany, Norway, the U.S., Australia, Canada, the UK are among the countries where the honor system isn’t any novelty."