This doesn't apply to NA FiST's. We basically have a few big ticket options and one package being the Recaro. With the FoST there are different trim levels, the same for the RS, RS1, RS2. This is how you order and pick the packages.
like stated before you could classify the Recaro package as ST2, ST1 is always the base. I honestly think it is due to the lack of options. Build a FoST and look at the differences then build a FiST, there is a lot of differences compared to the FiST. If you look at what's left after the Recaro option you would basically have Nav and a moonroof, well Nav is a given but a moonroof should always be a stand alone option, Ford likes to do the same with Nav on less expensive vehicles. If they went this route and tiered into ST packages you may have customer put off. They should of added HID's and then I could see it viable to group with Nav and create a ST3 pack.