Could you explain more? I do not understand how you can buy coins for free by paying coins for “weights” (what are these weights? What are they made from?). Also, what is the use for this? To check of your coins are real? Calibrate your coin scale?
15 kilograms sounds excessive though, I bet the bank clerks hate that trick ;)
One can of course go further and question if banknotes and coins should be called actually money. Today the nominal value is completely disconnected from what the metal is really worth, it's not like with gold coins back in the day. And once collective belief in the value is lost fiat money quickly becomes worthless. Zimbabwe and Venezuela are recent examples.