<warning type="trip down memory lane">
Red, weren't you one of the earliest developers of root cellars and such things? Don't I remember a warehouse that caused a "ghost" merchant to appear every so often? In those ancient days of yore before modding we often used trading posts as ersatz warehouses--put a bunch of stuff in a TP and it disappears from inventory.
</warning>
It is too bad that Banished uses weight for storage capacity, since a pound of stone takes up much less space than a pound of bread, but I suppose that you have to use some unit that can be standardized. I agree, though, that you shouldn't be able to store thousands of units of whatever in a little cart.