Comment by manquer

Well…

cash was and is still instant.

When doing large enough transactions that makes cash cumbersome, the slowness is a feature not a bug. We would want multiple reviews and time before it settled.

The value of $100 bill was much higher in 2000 and in 1969 when it became the highest denomination in circulation, so you could transact much higher value with a “wad of cash” than today.

Before 1969 we had bills up to $10,000 for a reason, they served like a credit note/T-Bill from the government, they were no longer needed after banking became robust enough for Cheques/P-Notes etc to replace them.

Paper Cash or Gold/silver coins before them are well understood solved problems, with thousands of years of experiments on size, security ,seigniorage and so on.