The metadata of being able to associate a transaction with an individual is much more valuable.
A business dealing with Cash is a legal liability because a transaction cannot be associated with an individual, especially if it technology.
Burner phones aren’t a thing in Australia. A lot of car dealers refuse to take cash payments due to laundering; it is legally safer for them to illegally reject cash than for them to get embroiled in more serious illegal activity.
Counterfeiting is also a concern as technology enables higher quality fake currency.