Did you even bother to read the links?
If you stay 31 days the form is required. Failure to comply may mean they can refuse you entry on your next trip.
It is true we don't require a visa for visits under 90 days. But if you stay 120 days an extension needs to be applied for.
The border folks on both sides have a great deal of power, and discretion. Some times you may run into a "tin pot God" on either side. I think there may be a lot more TPG on the USA side now.
Freedom polecat wrote:
Canadians don't need a visa to enter the US. You don't also have to fill out a closer connections form to enter and stay in the US. Most snowbirds do it as a precaution to avoid the hassle of the American IRS. But not necessary