Yeah, I'm pretty sure that's normal, disappointingly. Prestige owners might have a different arrangement.
I have a 2016 Premium Plus. When I took delivery, I noticed that I was only getting light on the right side of the cargo area, and made a mental note to mention it to the dealer. But upon closer inspection, I discovered the equivalent light "nub" on the left side of the cargo area doesn't even have a bulb or any wiring running to it (as also mentioned in the original post). It seems its only purpose is as a notch to hold up the cargo floor lid in the open position (and I wouldn't classify its holding effectiveness as confidence-inspiring, either). A light on both sides would have been nice, since the single one isn't quite as bright as I'd like. I suppose someone with some time on their hands could probably figure out how to retrofit one in there. All in all, the cargo area is the only part of the car that falls short of my expectations. I'd love lights on both sides, a 12v outlet, covered storage for the jack, a little more utility/finish in the existing side storage areas, and in my wildest dreams, a power hatch.
(UPDATE: Just did a quick search and found a 2016 Prestige for sale in Chicago. The photo of the rear cargo area clearly shows lights on both sides. Guess we didn't pay enough for that privilege!
But now I believe there's a good chance one could get parts to add it if so inclined.)