I know right?
I went through something like this with my players a while ago. They considered anything that wasn't worth carrying to be scenery or set-dressing, not really treasure...and what was and wasn't considered "not worth carrying" varied greatly. Copper pieces, for example, were frequently mentioned as not being worth the effort to haul out of the dungeon. One player in particular would get unreasonably angry about it, to the point of rage-quitting one gaming session and sending me angry emails for a week.
Not kidding.
A penny weighs 2.5 grams, so 10,000 of them is worth $100 and weighs 25kg--about 55 pounds. So if cp = pennies and gp = $, copper coins are worth 0.55gp per pound. My players considered this to be unworthy of effort, and would leave it behind. (And that one player in partuclar would take it further, accusing me of "robbing" them of treasure by giving out trash. "We've told you over and over again, we're not gonna haul that (expletive) around! So just forget it! Every time you say 100 copper, I'm going to write down 1 gold!"
Never mind the fact that they would loot every single weapon, shield, and fragment of armor that they found. In one adventure, they had collected over 30 scimitars from some skeletons, and they refused to leave them behind, even after I told them that they were battered and rusted and worth only 1gp each. These busted, 1gp scimitars weighed 3 pounds apiece...less value per pound than copper...and they were going to carry every last one of them into town, come hell or high water. "Each one of these is a gold coin!" I was told. "We're not leaving them behind!"
So I kinda stopped listening to their complaining from that point on. It was pretty clear that the problem wasn't the copper coins--the problem was they knew other, more valuable coins existed in the game, and they were trying to press me into using them instead. They genuinely felt that if I didn't convert everything into gems or platinum, I was somehow punishing them for dumping their Strength scores.
In the end, they got their wish: no more copper or silver coins. Instead, I converted all non-platinum coins that the monsters were carrying into an equivalent value of mundane armor and weapons. The encounter key says there are 100sp in that chest? Not anymore, now there's a shield. To this day, they still think they won that fight and I've never corrected them.