The mafia deals in cash...they own businesses like casinos, car washes and laundries that they can use to launder the money. They pay cash for houses and art...etc...so that they can then sell them and the money shows up as clean. None of their tactics are perfect and all require an elaborate network of contacts...LOL! Yeah, there is literally no way to move money around between various parties without the feds seeing it. That's why the Mafia went out of business.
Why do you think the Bidens would feel the need to break the law when just putting Joe on the record as owning part of the company would have allowed pretty much unlimited and legal payments to him? He was a private citizen.