People have questioned why EA would rig the World Trade HQ? The answer is in app purchases.
I spent an hour trying to find two yogurts for my plane. I got down to 90 seconds before it took off and bought 450 SimBucks for $5. Guess what, I found yogurts afterwards. A waiting system does not preclude a player from finding an item because a seller could list an item after you have that seller's marketplace in your 30 second window. The game play is running on a sever, so a weighting system could run effectively; maybe not even effectively. That may be why the delay to load the World Trade HQ. But the incentive is there for EA.
I get that companies need to make a profit. I can't say I would have downloaded the game if it was expensive. But the system needs to be fair. If you want to buy 400 Simbucks to purchase a basketball court, then go for it. But don't rig a "marketplace." In real life, that will get you a jail term; so, from a moral standpoint, a game shouldn't be rigged.