There's a reason scammers rely heavily on things like gift cards, it's because hiring mules is expensive and creates a trail police can follow back to the scammers. It requires them to be in the same locale as the person they are scamming. Mailing cash is also pretty dicey for the scammers because you have to send the mail to a valid address. That becomes something police can trace.
If you wanted to completely eliminate scams then yeah, you'd also outlaw cash.
You certainly could.
There's a reason scammers rely heavily on things like gift cards, it's because hiring mules is expensive and creates a trail police can follow back to the scammers. It requires them to be in the same locale as the person they are scamming. Mailing cash is also pretty dicey for the scammers because you have to send the mail to a valid address. That becomes something police can trace.
If you wanted to completely eliminate scams then yeah, you'd also outlaw cash.