I have to apologize, but you don't understand what the concept of "laundering money" means. It has nothing to do with tracking cash bills through serial numbers and it has never had anything to do with that.

"Laundering money" means that criminals make transactions in order to use cash they have from their illicit gains within the general economy, ie get it into a bank account and being able to declare where they got the money from.

> the reality is that if you withdraw $8k to pay for a motorcycle and hand it to a guy that sells you the motorcycle and then deposits it straight into his own bank account then yes, this is quite obviously tracked.

Not at all.