Ok, try this.
The pyramid interior is a temperature and pressure constant environment and the stone receptacle is the standard measure. The standard measure is used to certify volumes for trade in grain and other volumetric commodities needing a standard.
The pyramids at Giza have multi functions including indicating the solstice. indicating the true north south bearings, and permanent geodesic markers for surveys plus lots more.
The Giza pyramids are commercial in nature rather than religious
That represents a god-awful lot of work just to safeguard the weights and measures.
I think I’m going to go with the theory that a zillion or so tourists chopped off a little piece of the lid with a chicken bone for a souvenir since the t-shirt hadn’t been invented yet.