It is only a few months since Agnes-Marie Rodriguez moved to Fairfax from Los Angeles. Out in Fantasyland, the word "policy" doesn't have quite the holy ring that it does here in Bureaucratland. So Agnes-Marie can be forgiven for daring to utter the word "why?" the other day when a Fairfax retailer refused to accept her Visa credit card for a purchase of less than $10.

What did the man say by way of explanation? Why, "policy," of course.

Agnes-Marie complained loud and long enough that the retailer finally gave in. But why did he establish the $10 minimum in the first place? If he is like most retailers, he probably has three reasons:

1. He thinks it saves him administrative time in the long run. Putting together a batch of vouchers for $50 each and sending them in to Visa for payment is worth it, the retailer reasons. But doing the same amount of work for $2.50 vouchers isn't.

2. He thinks that setting a minimum will deter small-time fraud artists. At the very least, he reasons, a minimum will reduce the number of situations in which Theresa Teen-ager charges $8.59 worth of cosmetics on Mom's Visa, but Mom refuses to pay two weeks later because Theresa had taken the card from Mom's wallet without her knowledge. Too much hassle for too little profit, the retailer feels.

3. He hates credit card sales of any kind anyway, because he has to pay between 2 percent and 7 percent of each such purchase to the company that issues the card. A cash sale is a bird in the hand, the retailer thinks. A credit card sale is a bird in the hand three weeks from now -- and then only if there's no computer breakdown, postal delay or other unforeseeable monkey wrench.

But according to Dick Rossi, public relations manager for Visa International in San Francisco, stores that honor Visa -- and almost all other major cards -- are not allowed to set minimum purchase amounts.

"If we get repeated protests, we turn the name of the company over to the local bank that chartered it into the Visa system," Rossi said. "If the company refuses to remove the minimum, we'll take its privileges away."

According to Bill Bytnar, a senior vice president of Suburban Trust Company, which underwrites many Washington-area Visa cards, "The whole idea is to make it easy for the consumer to use the card. What the businessmen don't understand is that, if the consumer wants to pay for a $2.50 item by check, it'll take the clerk longer to handle that transaction than it will a credit card transaction."

But the more obvious fallacy, it seems to me, is the small retailer's fear of fraud. If you were going to try to put one over on a merchant, wouldn't you shoot the works and try to buy an illicit Mercedes, or fly around the world? Why risk disgrace or jail for a jar of cold cream? I can't believe it happens often enough to justify the small retailer's caution.

Besides, a retailer who puts a $2.50 item on sale and then makes it difficult for the customer to buy it isn't a businessman with a winning attitude. If all you want is the $10-and-up business, then don't put anything that costs less on the shelves.

Interestingly, Rossi noted that credit card minimums are "more common in the East than in the West. No, I don't know why."

Agnes-Marie Rodriguez thinks she does. She thinks easterners are "used to being manipulated. But it is all new to me." So she asked her Californiaesque "Why?," and got one Fairfax retailer to change his mind. If we veteran easterners followed suit, other minds might follow.