Did you actually see this very vehicle? Because if not then I think the simpler explanation is that the photo is from a 2wd 4runner and was somehow mixed in with an ad for a 4wd.
Otherwise you would have to believe that of all the hundreds of thousands of 4th gen 4runners that were sold between 2003 and 2009, for some reason in 2008 Toyota decided to sell ONE 4runner without a center differential. How the hell would that even happen?
The only other possibilities I can think of are that the vehicle was in an accident and had the dash rebuilt and somehow during the rebuild process they put a blank instead of the center diff lock button (which would mean that there is a center diff lock but the plastic plug and wire are somewhere behind the dash) or, less likely, that the CDL button was switched to a different location (which is possible, I suppose, since after all it's just wires - extend the wires and put the button wherever you want) but why would you do that when you have perfectly serviceable (and unused) buttons on the dash?
Again, unless someone here can verify that there was ever a 4th gen 4wd 4runner without a center diff I think the simpler explanation makes more sense.
EDITED TO ADD: This is one of the biggest 4runner boards on the internet. If Toyota made 4th gens without center diffs, wouldn't you have expected to see at least one person posting here and saying "why doesn't my 4th gen have a center diff?"
Also, I have seen 4th gens without roof racks. They're not common, but I've seen them around.
Have you ever seen Toyotas from the Southeast? I don't have to see this one to know the way they configure vehicles down here. How many Toyotas have you seen with Enkei wheels? They sell them here and they are OE and not aftermarket. That means that if you go to California and have an issue, Toyota has to take care of it.
As I explained before Southeast Toyota does things different. They bring in stripped down vehicles and add port install options because the margins are much better. It is cheaper for them to order them with steel wheels and swap on a set of Enkeis than to order the standard configuration. Because they are independent, they can order vehicles that you would never see through the Toyota owned distribution network.
I don't know if you are familiar with Toyota history, but their original distribution model they would send stripped down vehicles and let the distributor equip them. In the 70s, you could actually get a Toyota with no stereo. Slowly they bought back the distribution networks (technically they don't own the gulf states, but they conform to Toyota standards), but the JM Family has refused to sell or change from the original model.