I don't buy that. Wall Mart and other chain stores are notorious for attempting to trick customers into up-selling without their knowledge. Case in point? How many times have you found an item marked (say, on an end cap) for a really good price ... lets say a box of Rice Krispies for the 16 ounce size. But, on the same end cap they sneak in boxes of 12 ounce sizes, or make it so confusing with so many different tags it's difficult to determine just exactly which one is the "sale" item. Someone not watching will simply grab the most obvious, up front item and run with it thinking they got the advertised one, when in reality, the smaller box actually costs more than the larger one, that is actually the one on sale for the lower price.
I've never seen wood at a Lowe's or a Home Depot miss labled on the actual product, but I have found the shelf labeling to be horribly misleading ... unless you READ it very carefully. Case in point are true 8 foot 2x4's vs 7 foot 2x4's. Yet, they will be side, by side. Easy to grab the wrong one ... which I've done a few times until I wised up.
So no.... I don't follow the "innocent management" theory at all. It's a deliberate attempt at deception.
The OP was very, very smart in questioning the label. And he was very, very smart to check it out too, and not just arbitrarily grab the first piece of wood and run with it.
That's OK folks, no one believe me either 20 years ago when I tried to sound the alarm that big brother was monitoring everything you do via your new cell phone, new automobile or your new internet operated appliance either.