I've mostly only heard unsafe from people who haven't taken any form of public transit in 25+ years
Here's a crime sampling from a 2017 article in the Detroit News about bus safety:
Two DDOT passengers were injured Nov. 29 after someone from a moving car shot into a bus near Hamilton and Oakman in Highland Park. The injuries were not life-threatening, police said.
An attempted robbery ended in a shooting Sept. 12 as a 33-year-old man exited a bus near McNichols and Runyon. Police said when the shooter found the victim had nothing to steal, he shot him anyway.
On Aug. 12, a man on the Grand River bus exposed himself to a female bus driver before touching her breast.
A 19-year-old man on Aug. 1 was shot in the hand while riding a Livernois bus following an argument with another passenger.
An argument between two passengers that started July 28 on a DDOT bus escalated into violence after the two men deboarded the coach. Police said a 29-year-old man was using profanity on the bus, within earshot of an older man and his family. The two men argued, and when they got off the bus at the terminal at 8 Mile and State Fair, the older man shot the victim before running away, police said.
On April 23, a man shot at a bus after the driver kicked him off. Police said a man and woman were arguing near Harper and Whittier on Detroit’s east side. The woman got onto a bus hoping to elude the man, but he followed her onto the coach. After the driver ordered the man to leave, he stepped off the bus and fired a shot.
Police say on March 2, a DDOT bus was pulling into the Rosa Parks Transit Center’s loading area when an irate passenger assaulted the driver, who drove his bus onto a curb and struck a pole. No serious injuries were reported.
On March 6, a bus driver stabbed a passenger in his hand after she was attacked. The driver had tried to get the man to get off the bus, which prompted the attack, police said.