Is there a back story to the love relationship between the police and doughnuts?
Back in the day doughnut places that served coffee were one of the few places open late at night because that's when they would usually be making donuts for the next day, especially in smaller towns. So they were common stops for police officers who worked the graveyard shit and they would often give them a discount or just free coffee and a donut so they would come by. The more police officers visited, the lower the crime rate was.