True, but police are usually given headshots and information on wanted criminals. If they see Barry the Boy-Butcher taking part in a festival where mafia take centre stage, would they let them?
Yakuza member isn't like any typical criminal who worked alone, they have organization.
If police wanted someone who's done serious issue like murder of civilians (not murder between yakuza gangs, that's a different case), they'll just contact the boss of the organization and the boss will hand him for them if it's proven.
If it's just a street-level crime, the police could just inform the names and let the boss decide whether to punish their subordinates themselves or hand them to police.
Historically, Japanese police and Yakuza maintained a symbiotic, often cooperative, relationship based on
maintaining public order, where police overlooked, or even utilized, organized crime groups to manage street-level crime, and in exchange, Yakuza restricted violence against civilians.
