Building complex systems involving humans is hard because humans are flawed. The best thing we’ve come up so far are systems involving extensive checks and balances to prevent thing happening too rapidly and without necessary oversight and even then it’s a tricky part to balance.

For the record, I’m not for entirely cashless society but organisations that are cash heavy have proven to be source of many headaches. There is a balance to be found on thresholds and barring some types of businesses from using cash and where digital money transfer is required. Banks and other money transfer entities will have to deal with scenarios where malicious parties will try to obfuscate their intent outside of those thresholds.