Scott you said :
A typical ancient granary would not match the colossal size of the Pyramid Recovery Vaults. The Recovery Vaults had to be made highly visible in a barren landscape so that they could be easily found. Their internal storage chambers would require to be sealed with considerable security/blocking measures to deter/prevent casual looting. You would not find such heavy security measures in a typical granary.
I'm trying to picture RV's and how they would have succeeded as such, and Pat's questions are plaguing me. You probably included other items besides food in the RV. Since the survivors would have gawked at the pyramids, scratched their heads and walked away in search of food, maybe the focus shouldn't be on food. Survivors would have been sorely lacking in tools, probably only having stones and ropes and it would take a while to set up a smelting plant, (gees, sounds like the AE's) by the time an entrance was made food may not have been an issue. Or are you thinking the RV's would also have housed the survivors who of course knew how to get out.