It won't. This tax is ultimately unenforceable since it would be trivial to put down a family member as living at your vacant house. All they would have to do is collect mail there and it would be virtually impossible to prove otherwise.
Not true. It's fairly trivial to see if someone is living in a specific location. A simple bank statement shows where you've been spending money and tends to be good indicator of whether you're in Vancouver or not.
Canadian government already has a program like this in place for recent immigrants to ensure that they actually reside in Canada during their permanent residency period. Over the past fews years many people immigrated to Canada and left after landing to become 'convenient Canadians' five years later. Canada already knows how to do this.