Probably institutional memory from super-hyper inflation after WWII.
Interestingly, I was searching last night for reputable sources to buy Gold/silver coins and bullion. I was thinking of the American Eagle series and the Englehard blanks and ingots.
Some dealers offer low prices with high shipping. Some offer higher prices with low shipping. Some only accept large orders (thousands of dollars). Delivery offers the risk that someone will recognize the name of the dealer sending you packages. I recommend local stores where feasible.