Personally, I don't understand how one time use money cards would have any preventions to prevent the same thing from happening. One could send someone to buy a stack of them with a wad of cash, and the original store the cards are delivered to might be tracked, but after that, what else is there? The money gets transferred out, and they might not even know what the purchase was.
There are more private cryptocurrencies, but it's near mathematically provable that all with sufficient transaction history and brute forcing capability are traceable. In the case of law enforcement, all they have to do is sit in these transactions until the have the CPU power to break them. I'd had to be the one that used cryptocurrency to buy something illegal knowing that 50 copies of the ledger exist on other people's computers.