The Santa Claus Compromise by Thomas M. Disch

The Santa Claus Compromise by Thomas M. Disch (Crawdaddy, December 1974) opens with the Supreme Court giving children of five and older full civil liberties. Various societal changes ensue, including the ability of children to work as reporters: this leads to Our Own Times’ Bobby Boyd and Michelle Ginsberg running a story stating the there is no Santa Claus!
We learn about the evidence that the pair have uncovered to support their story (Bobby finds receipts for items similar to the gifts Santa brought him, etc.) and, when the news starts breaking through to other youngsters, opinions change; eventually there is a serious economic impact when people don’t buy Xmas presents and other merchandise.
Eventually (spoiler), the President has to take the two intrepid reporters to the North Pole to restore the status quo ante:

What they saw there, and whom they met, the whole nation learned on the night of January 24, the new Christmas Eve, during the President’s momentous press conference. After Billy showed his Polaroid snapshots of the elves at work in their workshop, of himself shaking Santa’s hand and sitting beside him in the sleigh, and of everyone—Billy, Michelle, Santa Claus and Mrs. Santa, the President and the First Lady—sitting down to a big turkey dinner, Michelle read a list of all the presents that she and Billy had received. Their estimated retail value: $18,599.95. As Michelle bluntly put it: “My father just doesn’t make that kind of money.”
“So would you say, Michelle,” the President asked with a twinkle in his eye, “that you do believe in Santa Claus?”
“Oh, absolutely, there’s no question.”
“And you, Billy?”
Billy looked at the tips of his new cowboy boots and smiled. “Oh, sure. And not just ’cause he gave us such swell presents. His beard, for instance. I gave it quite a yank. I’d take my oath that the beard was real.”

A droll story about the mercantile aspects of Christmas.
*** (Good). 2,000 words.