The company Yellow, a freight-moving trucking concern that has been around for nearly a century, is now in bankruptcy. Why? As usual, there are a lot of reasons: The intransigence of the Teamsters, a series of bad judgments by the managers, and a private equity firm's desire to fish in troubled waters all enter the picture. But what I want to talk about today is the nature of the business that Yellow is in. (It has no connection, by the way, with Yellow Cabs. Yellow is simply a distinctive and easily distinguishable color on the move, so it was a natural choice for two distinct sets of company founders.) Yellow is in the LTL business. This means that it contracts to move freight that constitutes less than a full truckload -- less than enough material to fill up one of those ubiquitous trailers one sees on the road. Though there are other firms that work for shippers willing to fill several full truckloads at once, the segment of LTL freight is a critical p...