I take your point: the hassle-free crossing between Canada and the US are a thing of the past, and requiring this added piece of documentation is going to cause havoc at places like Douglas/Blaine, at least for the first wee while.
(presumably they will phase it in?)
It has been a long time coming, but it is a manifestly more sensible scheme of arrangement during a time of war. Hassle-free crossing is an ill-afforded luxury during a time of war when the Enemy has shown, in the past, a willingness to use such conveniences to his advantage.
(I’m not thinking of 9/11 here, but rather the Y2K bomber who crossed at Port Angeles)
Will this apply to those who must send their children across the border to go to school, go to the hospitals & doctors, pick up their welfare checks at their P.O. Box & spend their pesos at American stores?