I have wondered about them all being owned by the same company for those reasons. I also wondered if the system looks similar because at the end of the day its GM's inventory system that they are providing access to and selling from.
I ordered a new clock spring 2ish weeks ago for my truck from Tasca to do the heated wheel swap. I did everything I could to ensure that I ordered the right part number but I also put in my VIN which was a mistake on my part. A few days after the order someone contacted me to make sure it was what I wanted because it didn't fit my VIN according to the system. I explained that I was fairly sure and if they could confirm it was for a same year truck just with a heated steering wheel that I wanted to continue with the order. Then crickets. A week later they sent me the same email to which I just replied its fine and to send it out.
I understand they don't have the ability to say if it will work with my truck doing this mod, but they should be able to easily see if it fits a truck with a heated wheel from the same year.