That's why, Carpe, I have a sneaking feeling (based on very little logic) that the explanation that another even more massive haul was going through at the same time holds water.
If you wanted to pass through a couple of deals at the same time, why not use the frightened, easily caught, gullible foreigners to distract the attention of the police.
Of course there is another theory - again, completely made up with no evidence whatsoever, that the police in Peru needed a big haul to "prove" to the international community that they were doing something. I think there has been a suspicion for some time that the authorities in some of these airports are taking backhanders to let drugs through.
Late MIL's carers were a married couple from Peru, and they used to laugh at me when I muttered darkly about corruption in here in Italy. They seemed to think that it was significantly more of an issue back home. And all that you have described was alleged to happen on a regular basis in Thailand.
Plus there's the snitching to the police by the lower down in the food chain when in a sticky situation of their own. The tit for tat informing between competitors and rivals. The rank incompetence of embryonic drug-lord wannabes. And some people blab in their guesthouse, never imagining that somebody within hearing might tell somebody else, who might take exception and tip off the police what they are intending to do.
I think the "50 ways to come a cropper at customs despite all the promises it's no problem and everything has been taken care off" is worth mulling over by anybody tempted to consider being a mule. If somebody is prepared to be a gangter, or a drug lord then it's not really all that surprising that they might tell porkies, wildly understate risk, or even drop a mule right in the shit deliberatly if it suits their business purposes.