Mystery solved! Ever wonder why Soviet department stores are empty while those in capitalist countries are full of merchandise? Well, a Latvian educator has answered the riddle in a Soviet publication. "People in capitalist countries do not earn enough money to buy such products and therefore they remain on the shelves. The income of the Soviet people has been rising steadily so that now they can buy everything they desire. It is the buying power of the Soviet people that keeps store shelves empty." Take that, Agatha Christie.

Everyone knows that the cost of living is up because of government. But so is the cost of dying. Coffin-maker Roger King of Wendell, Idaho, wants to sell his caskets directly to the public. But a state law that gives that exclusive right to morticians threatens to nail the lid on his plan. An Idaho trade association for licensed morticians has sicked the state on King, who offers lower prices than mortuaries. King says his plan would save taxpayers money, because Idaho counties are required to pay for burial of indigents. Under present law, the counties have to buy caskets from funeral directors, who naturally charge a lot more. Is this what the welfarists mean by cradle-to-grave "protection"?

Cab drivers in Las Vegas are acting like the posterior ends of their competition. The hackies galloped into a courthouse to put the reins on "unfair competition" from the horse-drawn carriages that carry high rollers on the famous "strip." A judge finally lifted a restraining order that prevented the carriages from operating on the tourist thoroughfare. Horse sense finally prevailed.

We all know about chefs who won't eat in their own restaurants, doctors who won't be treated at their own hospitals, and US auto workers who buy Japanese cars. Now consider this. Michigan school teachers are twice as likely to send their own kids to private schools as the rest of the state's population. And in Chicago, 46 percent of city public-schoolteachers send their own children to private schools, as compared with 22 percent of Chicagoans at large. Maybe they know something.

What's the bottom line? The New York City Transit Authority bought 325 Japanese-manufactured subway cars with rather tight-fitting bucket seats, measuring 17 inches across. This presents a bit of a problem, since the average New Yorker's backside overflows the bucket. That's what Councilwoman Carol Greitzer learned in her "First All-American Tush Tally," a random sampling of 23 rear ends. "This survey is not an end in itself. It's a means to an end," she said, wondering why the Transit Authority couldn't have performed the same inexpensive survey (she used a $1 tape measure) before spending millions of dollars (lots of them taxpayers') on the bottom-busting cars. Looks like the Transit Authority's the butt of yet another joke.

Real men don't need umbrellas. That's been the philosophy of the US Army up to now. A GI in uniform is never to carry an umbrella, rain or shine. Drier heads are trying to prevail, and the Army Clothing and Equipment Board is considering purchases of the raingear. But one officer close to the board is skeptical. "A lot of the senior officers don't like the idea because they think it's too wimpy," he says. The Air Force has allowed the use of umbrellas since 1979. But the other services allow only women to use them because of the "difference in hairstyles," says Army Major Robert Mirelson. Are Americans really being served by folks who don't know enough to come in out of the rain?

Safety in numbers? More than 1,000 men celebrated the King of Thailand's 57th birthday by submitting to free vasectomies. The assembly-line sterilization, sponsored by a population-control clinic, fell short of 1983's unofficial world record of 1,190. A doctor who has performed 5,000 vasectomies hastened to comment that "numbers are not important. It is the quality that matters." A festive time was had by all. Prizes were given to all the men, while a rock band sang the praises of contraception. The clinic distributed among the newly vasectomized men T-shirts bearing the proud slogan "I am safe now."