It's a little more complex than that... LSG in CLT charges them for each additional item to store/process and each additional catering spec, so there's a cost/benefit analysis that goes into adding new service tiers to a station. AA has proven they're more than happy to add additional catering services at different stations where it makes sense. It's not just a cost thing though, it also complicates things for the caterers. The more complicated the procedures, and the more different type of inventory the caterer has to stock (and the more stations you spend the serviceware out between), the more miscaters you get statistically. Things run smoother, and you get to spread the extra fixed costs out among more flights if you have more than one flight at that catering station using the extra specs, but sometimes even just one one flight a day is worth it (like this).