On the surface, the disappearance of the Street Aristocrats was not that conspicuous. They were the underworld organization, after all. The Sewer Snakes and the Demon Gang took over to collect protection money from common business owners. For these business owners, they didn't care whether it was the Street Aristocrats or other organizations, so long as they let them do business in peace after they paid.
It was the same with the authorities. As long as they received their cut and the organizations didn't cause too much trouble, they left these underworld organizations alone.
The authorities didn't trouble the Sewer Snakes and the Demon Gang for the massacre they did on the Street Aristocrats. The victims of that conflict were solely the underworld members. No civilians were harmed. The civilians didn't even realize there had been a big fight that night. Almost all of them were at the festival hosted by the governor.
