This old topic for items found in Australia... and more examples from America.
Those ones are obvious... but since it happens, how can you be sure that an item that is no longer sealed when it arrives to you, hadn't been swapped out with a KO or a defective toy. Even if you do notice something wrong with it, you can't be guaranteed a replacement (even if it is still in stock), and even if you do, how much extra time and hassle is that. All avoidable if it remains sealed, or single-taped.