Because they're from WCP, not VEXPro. RC would be the better person to ask, but as I understand it, the two only act as distributors of some of each other's products - they are still their own independent companies (hence why WCP only sells vexpro items and not vexiq or vrc things, and why VEX doesn't sell WCP gears and sensors, among other things).

I'm not too sure about the backorder status (once again RC is the person to ask). Emailing him is the best way of getting information that you don't know, and it seems so many people have questions but don't ask, so please do ask. I'm no official affiliate of the company, but I imagine it's hard for them to know what questions need answering and what could use some clarification if nobody asks them.