In most traffic accidents involving a fatality, criminal charges are not laid unless there is evidence of dangerous driving.
For a criminal charge to be laid, the prosecution has to show that the driver intended to commit the act. Meaning that the driver intended to do something that was planned that caused the fatality.
In traffic accidents, usually the driver did something, neglected to do something or made a mistake in driving, but the act was not planned. In Canadian law this is called intent.
Normally where there is no intent to commit a driving act, there will be no criminal charges.
Criminal charges would only be laid where the police or prosecution can prove that the driver did something so obviously wrong that they should have known that their actions could have caused the serious incident to occur. e.g. how did it happen and what occurred prior to the accident.
For a criminal charge to be laid by the police, there must be a “marked departure from the standard of care expected from an ordinary driver”.