I agree with you Jason. Todays cache is most likely to be paper, unless someone has stolen a coin collection from somewhere. Sure, old people still hide bottles of coins, but CASH also, The coins are usually just pocket change that is hidden, mostly not even silver. After passing away, my fathers house had money stashed everywhere, some in the usual places, others in specially made compartments, but mostly just in a plastic bottles hidden among the other junk he collected. When I would make a dump run for him, he always said, "thats money, dont throw it away", of course I thought he was just refuring to the usual trash he collected, but later I found that these plastic bottles were his favorit hiding place, so thats why he was worried. If he ever hid anything in the yard, then it was hidden good, but he has so many little sheds build, full of junk, that im sure these were his main hiding places, and the same can be said for all the other caches around. Our houses all have hollow walls, and celings have insulation, so these are the best places, not in the garden when people just had log cabins or very small houses. There are just too many places to hide a cache inside nowdays, and dont have worry about the neighbors seeing. Basements are even better, but not a crawl space, unless its a criminal stash. The normal person likes an easy place to "bank", and cant be bothered with digging in the rain, and paper money needs a dry place to stash, not in the onion patch.
I think that most older people that stash money, forget where it was, and just make a new stash somewhere, so may have dozens of hiding places, but not in a place where they need to work at getting it.