I believe it could be related to the bail system.
I can't specifically relate to the violence on public transit, but the overall violence.... Chief Myron Demkiw of the Toronto Police Service would tell you that he has statistics that are absolutely alarming about the number of people who are released on bail who fit the definition of a repeat violent offender using a firearm in the commission of an offence, who then reoffend and reoffend and reoffend, up to three times; 17% of Toronto's homicides fit into that category.