Because we don't have a cultural history of violence, like say, the U.S. In addition to that, we have strict gun laws and most people in Canada do not own firearms. Also, we're a population of close to only 40 million people with lower rates of poverty, higher educational standards for most citizens and overall better employment opportunities for the general population. Canada is definitely not perfect and we have our own share of problems at the political, social and economic levels throughout our cities but in terms of violent crimes, our cities have been developed and shaped differently than U.S cities over the past 100 years, thus, a vast difference in crime rates.