But what is the throughput of people in detroit? Detroit has fairly few residents compared to the number of people who go into detroit to a casino/dining/sport

But what is the throughput of people in detroit? Detroit has fairly few residents compared to the number of people who go into detroit to a casino/dining/sports game. The chance of one of these robberies happening to a resident is much less than 9% I would argue. Also, you're forgetting about the "Broken window effect" which says that crime flees an area when the surroundings simply look better.