Is it to stop you paying for your carrots, or your rent (et al), in potatoes.. or trading your potatoes for gold rather than fiat to avoid taxation? Governments

Is it to stop you paying for your carrots, or your rent (et al), in potatoes.. or trading your potatoes for gold rather than fiat to avoid taxation? Governments are incentivised to force all transactions in terms of fiat. That said, I agree it's frustrating that you are liable for what are unrealised price changes (IMO it's not profit until it's in the bank).