When racing fans left Laurel opening day, many of them found flyers on their car windshields advertising (of all things) the Daily Racing Form.

Just a week earlier, that would have been unthinkable; the Form had one of the most secure monopolies in American business. But when Laurel started selling a program that contained past performances, the Form was suddenly jolted out of its complacency.

The burgeoning competition between the Form and Sports Eye, which compiles the past performances Laurel uses, is going to demonstrate the very best features of capitalism. These two corporate adversaries are going to be vying to offer a superior product, and the consumer is going to be the winner.

At this point, the Laurel program's only competitive advantage is its lower price. It still must prove that it can offer information as accurate and thorough as the Form does. So far the program hasn't done that.

Considering the enormous amount of data it processes, the Racing Form is amazingly accurate. I can remember only a handful of times in my life when I have spotted an error in the Form's past performances so significant that it could make the difference between cashing and missing a bet. Yet in Sports Eye's first week of operation at Laurel it has already been guilty of one such blockbuster error.

Racing fans analyzing the Japan Racing Association Handicap, which was run over the Laurel turf course Saturday, might easily have loved the credentials of a colt named Valiant Lark. His past performances in the program showed that he had raced once before on the turf, at Monmouth Park, and had won impressively by five lengths.

That would have a legitimate basis for betting Valiant Lark at 5 to 1, except for one thing: the program was wrong. Valiant Lark had never raced on the grass in his life, and he was soundly trounced Saturday. That is the kind of error that can cost people money and make them conclude that saving 75 cents of the cost of the Racing Form is being penny wise and pound foolish.

But if such errors prove to be rare, and the program retains its credibility, then the crucial battle between Sports Eye and the Form will be waged over workouts.

In Maryland, as in most states, the Form hires clockers and provides all the "official" workout information. The operation is a costly one and neither Laurel nor Sports Eye has been willing to bear that expense. So the Form offers workout information while the program doesn't.

This is not as much of a selling point as it might be, because the unreliability of the Form's workout information is legendary.

So racing fans have reason to be surprised by what has happened in Maryland lately. On Wednesday, Shadowfax was racing after a five-month layoff and showed a pair of excellent workouts; he won at 9 to 1. On Friday, Jetta J. was running after a three-month layoff and showed a six-furlong work in 1:13 4/5. She won at 4 to 1. On Saturday, Annie's Dream came into a race with five-furlong works of :59 3/5, 1:00, :59 2/3 and :59 3/5. She won impressively at 9 to 2.

The Racing Form's workouts have become--for the first time in memory--a useful handicapping tool. The competition from Sports Eye must have spurred the Form to do a better job in this crucial area.

But Laurel officials have a visionary idea of how they can outdo the Form in reporting workouts. "Next year," president John Schapiro said, "the problem of workouts will be solved if we get the cooperation of horsemen. We want to use an electronic adapter that would be fastened to the crown of a horse's bridle and would be activated at the pole where the horse starts his workout. We would time the workout electronically."

Race tracks could have used modern technology to time workouts before now; the Daily Racing Form should have made an effort to provide more accurate workouts before now. It wouldn't do these things out of a good-hearted concern for the interests of the racing fan. But when it has a profit motive, and when it has economic competition, it will do these things--and the public will benefit. It's enough to make you believe in the American way of life.