This is probably in response to this incident:
http://www.torontosun.com/News/2007/06/21/4279163.html
Recap: Two Yankee doodles were racing down a highway that saw two huge street racing accidents in the past month, one of which killed a truck driver who swerved out of the way.
But to be honest, like any law, people blow it out of proportion. It's not like they're out to get you if you haven't done anything wrong. The Canadian coppers aren't like your average Georgian or Texas State Trooper... The law is probably in effect just so that if they catch you street racing, not only do you lose your license, but you get punished severely.