Thanks for finding and posting this, from what it seems there might be one way to lock a seat in.The "tracks" only come with the appearance package, and are visual. The picture of the slots in the equipment guide tells the story more accurately. Its not a "track", its a slot. It does not look to me like they are symmetrical.
Maybe it has to do with safety of load regulations here and if so we might see that change in the future where it's in line with what the EU has, i heard about something like that happening years ago.Actually, what a guy at MB told me was that the tracks, for various reasons, are not US market compliant. They'd have to design, engineer, and certify a whole new system for here, while the subframe slots are compliant. Nothing is ever simple in the highly regulated auto business.