I am aware of that, but in Alberta you can go to the ministry of health and say I am moving permanently to Alberta today. Coverage will start there and then
It's not as simple as saying you are moving to Alberta permanently. You still have to provide proof of Alberta residency when you sign up. Also, you'll still have to pay out of pocket for any health service until residency validation (although you are reimbursed later once you can show you were entitled to coverage). Coverage may start on day one, but it doesn't mean there's no out of pocket cost from day one.