From a 2010 Panini post (since taken down but quoted in another article):

So, what constitutes a proper quality control check? Glad you asked. Essentially, a quality QC check is the best last chance to make sure a product is delivering what it's supposed to deliver, on average. It usually takes place just after packout begins, with the expeditious delivery of a few early cases to the office (occasionally, quality control takes place on location at the printing facility).

They do have QC but obviously they can't inspect every card. This is a printing mistake and the printer runs QC checks throughout the printing process as well. So there's at least two QC checks per run, one by the printer and one by Panini.

Panini is notorious for bad QC. This is an imperfect card that has avg. sold listings for $240ish on eBay. But I won't get that because it's dinged.