Well you hit on a good point, the need to be wary of counterfeit currency. There were disincentives to using gold and silver in daily usage. The golden koban co

Well you hit on a good point, the need to be wary of counterfeit currency. There were disincentives to using gold and silver in daily usage. The golden koban coins (Ryo), as well as silver and brass coins, formed the official Edo period currency. However, the amount of gold used in minting koban declined over time, and there were also regional, unofficially minted koban, so it would have been relatively straightforward to try to create counterfeit koban. In addition, Spanish silver dollars were used unofficially, despite not being the official currency. The actual value of all these coins could fluctuate on a seasonal or even daily basis, and was tied into the price of rice. All of these are reasons to not deal with exchanging metals for daily transactions, hence the prevalence of credit-based transactions.