At this point, Donnie paused and asked Nucky, "Do you know how many tycoons in the United States have laundered their ill-gotten gains into legitimate money through the Surf Hotel?"
The banking industry, especially the private banking sector, cannot withstand scrutiny, especially in the West. There was a joke that said if all officials were rounded up and shot without trial, although there would be casualties of innocence, the move would absolutely be worth it.
This is also true for the private banking sector. If any investigation is conducted, no private bank is immune to scrutiny.
Thus, most consortia in the United States have their own banks to ensure the security of their funds, nobody wants to become the next casualty!
Even consortia without their own banks will seek close allies!
This is precisely why Donnie must have his own bank; his funds are not clean. Just the money earned from the Bootlegging Empire is enough for any government to crack down on Donnie's cash flow!