If one judges by the amount of time, money and effort that is devoted to political primaries, one must conclude that they are among our most popular diversions.

True, pleas for campaign contributions to finance the heavy costs of so many primaries seem to go on endlessly. The moment an election is over, we bgin filling dozens of political war chests for the next set of primaries.

But this is such a wonderful way to spend money! It is such a great entertainment bargain! In return for our cash we are provided with a minimum of six yards of political news in each day's newspaper plus a cumulative total of seven hours and 13 1/2 minutes of network and local political news reports during each broadcast day. In addition, there are those captivating paid political announcements.

Best of all, though, are the political speeches for which candidates buy broadcast time. Like other prime time entertainment programs on TV, some of the primary campaign speeches are funny, some are sad, and some border on tragedy. Where else can you get that king of bargain for your entertainment dollar? Where else can you find programs that you can be sure will continue on, month after month, without danger of cancellation when their ratings dip a little?

The one weak link in our election system is election day itself. It is uniform throughout the nation, always held on the same day everywhere, and as a result devoid of continuity, sustained interest or suspense. What we ought to do is let each state decide on its own election date, or dates. Some states might want to vote for representatives on one day, senators on another, and presidential electors on a third -- perhaps in August or December. Now wouldn't that be fun?

Of course it would also cause a huge increase in the cost of running for office, and it would drive the average American right up the wall.

Why can't we have one uniform day for primaries just as we have one uniform day for national elections? GETTING INTO A CAR

At irregular intervals, I feel sorry for the married woman with whom I have been living for 47 years and I take her out to dinner.

When we emerged from a restaurant about two weeks ago, it was quite chilly. I hurried to our car, parked nearby, to unlock the door for her.

But as I did, I noticed a husky young underachiever who had been loitering nearby on the dark and deserted street. As soon as I approached the car, he began sauntering toward me. By the time I was at the door, he was 10 feet away.

Instead of stooping over to unlock the door, I remained erect, turned my back to the car and looked him straight in the eye. He hesitated for a millisecond, then changed course and veered off down the street. My wife, huddled down into the collar of her coat, said impatiently, "Will you unlock the door, for Pete's sake? It's cold out here."

Only when the loiterer was out of range did I say, "Yes, dear." I unlocked the door and my wife got in. She still doesn't know what happened.

In the past few days, several prominent Washingtonians were in the news because they were accosted as they were unlocking their cars. Dozens of less prominent persons suffered the same fate without being written up.

A friend of mine was shot. He died a few days later.Columnist James J. Kilpatrick was roughed up on the morning after my encounter with the underachiever. Kilpatrick said later that when he was accosted he feared for his life.

His fears were well founded. Thousands of people are robbed in this area every year. In Washington alone, 197 people were murdered in 1978. In 1979, another 189 were killed -- many of them during the course of robberies. Area-wide totals are much larger.

My observation of street-wise people -- policemen, detectives, private eyes and others who have learned how to survive in the jungle -- indicates that it might be useful to pass along two observations: (1) Before an alert person unlocks his car, he takes careful inventory of what kinds of unsavory characters are close enough to do him harm. A fierce scowl and direct eye contact will very often cause a mugger to go off in search of easier prey. (2) A street-wise person never enters his car by sticking his head in first. He gets into the habit of turning his back to the vehicle and putting his hind end in first. Carless people get zapped when they are helpless -- half into their cars and half out.

Even if the married woman with whom you live is shivering in the cold, you must take time to look about you. Later, you can explain to her that it's much easier -- and a lot more fun -- to releive a momentary chill than to remedy the damage done by a black-jack, a knife or a gun.