"This note is legal tender for all debts, public and private." If I buy you lunch today, you can pay me back next week. We're not "cash handling business[es]",

"This note is legal tender for all debts, public and private." If I buy you lunch today, you can pay me back next week. We're not "cash handling business[es]", so we wouldn't have to scan. Second, I don't think it's technically possible. For companies that do business across state lines, sure, but within a state's border, interstate commerce laws don't apply. Each state would have to enact a similar law. And best of luck with that.