slowness is a feature, not a bug, in some social situations. Most modern Americans have not experienced that kind of situation. One of the elements missing here is control - who has control over the transaction, and what are the practical methods to resolve dispute.
Cash is not great at scale perhaps, but it is great for the individual in times when trust is gone, where there is unequal power relationship, and where there is real corruption inserted into ordinary transactions.
As an American with some knowledge of history, I support cash, paper checks, and electronic transfer. without a doubt.