Yes, I was talking about the physical act of paying - and the form that payment could take when you're trying to extract taxes out of cash-poor subsistence peasants - and how in that kind of world, taxes in a single, fungible type of good (food, days of service in agricultural labour) are common.

The economy being diverse, and not just a bunch of peasants barely making ends meet is a great reason for me to not be taxed in rice. I don't grow rice. I don't know anyone who grows rice. I'd have to take money, buy rice, give it to the taxman. This is... Not ideal. (Just like the taxman getting paid in <whatever random non-food good I produce is not ideal.)

Even in pre-industrial societies, where where taxes-in-food were common, city-dwellers paid taxes in cash.

But just like how you don't actually hand over stacks of paper to pay your taxes, you wouldn't need to actually pay in literal bags of rice in a world were rice was currency. I would imagine any economy that kept using rice as currency past the point of subsistence farming would develop tokens.