There's a great article in the New York Times on Japan's insanely complicated trash-sorting requirements:

YOKOHAMA, Japan - When this city recently doubled the number of garbage categories to 10, it handed residents a 27-page booklet on how to sort their trash. Highlights included detailed instructions on 518 items.

Lipstick goes into burnables; lipstick tubes, "after the contents have been used up," into "small metals" or plastics. Take out your tape measure before tossing a kettle: under 12 inches, it goes into small metals, but over that it goes into bulky refuse.

Socks? If only one, it is burnable; a pair goes into used cloth, though only if the socks "are not torn, and the left and right sock match." Throw neckties into used cloth, but only after they have been "washed and dried."

How can the authorities enforce such a hopelessly complex system? They don't have to. Old people with too much time on their hands do it for them.

Enter the garbage guardians, the army of hawk-eyed volunteers across Japan who comb offending bags for, say, a telltale gas bill, then nudge the owner onto the right path.

One of the most tenacious around here is Mitsuharu Taniyama, 60, the owner of a small insurance business who drives around his ward every morning and evening, looking for missorted trash. He leaves notices at collection sites: "Mr. So-and-so, your practice of sorting out garbage is wrong. Please correct it."

"I checked inside bags and took especially lousy ones back to the owners' front doors," Mr. Taniyama said.

This has actually happened to friends of mine here in Tokyo. And shortly after I moved to a new house, an elderly woman came to my door and let me know that I was throwing away my (correctly-sorted) trash at the wrong collection site. Why did she care? Well, she had organized a rotating neighborhood clean-up list for that particular site, and it wasn't fair of me to leave my trash there if I wasn't going to take a turn cleaning it up. (Bear in mind that we are talking about a public trash collection point, not a part of anyone's private property.)

Yeah, sure, community involvement is what makes Japan run so smoothly and harmoniously, yada yada yada. But it's also creepy, in a big-brother sort of way: Trust no one. That kindly old gentleman down the street could be watching you.

One thing I like about New York is the way people mind their own business. There's a sense of privacy that comes from knowing no one would bother to search through your garbage, much less take it upon themselves to bring it back to your front door.