Kevin Drum reads a New York Times article about holiday retail sales and bangs his head against the wall as he observes the story citing nominal sales figures: "Question: why does this happen so routinely?"
It almost certainly happens so routinely because many reporters and editors don't really understand what they're doing. Reputable colleges hand out degrees to people who have almost no understanding of quantitative methods. I recall that Larry Summers observed in his inaugural speech that "We live in a society, and dare I say a University, where few would admit—and none would admit proudly—to not having read any plays by Shakespeare or to not knowing the meaning of the categorical imperative, but where it is all too common and all to acceptable not to know a gene from a chromosome or the meaning of exponential growth." Journalists, being basically a species of writer, tend to come from humanities backgrounds even though we deal with quantitative issues all the time. Journalism schools might help close the gap by making people take "math for journalists" classes (the concepts of statistical significance and margins of error in polls come up constantly, for example, and are often dealt with very poorly) but as best I can tell they normally don't.