Well, I have a Nexus, which has always provided hassle free cross border experiences for me, and now it's not a valid travel document? And the Canadian certificate of citizenship, which is the proof the Canadian passport office requires of non Canadian born citizens to receive a passport is not adequate proof of citizenship for travel? I'd buy an ESTA, but as a Canadian citizen, I can't get one. Sorry, Canada, you developed the Nexus framework, too late to change the rules now, with a redefined definition of what constitutes a valid "travel document"
The Canadian government seems to want (in my specific case) U.S. airline employees to enforce nonsensical Canadian immigration regulations...
My experience is that airline employees consistently make issues that the front-line border agents do not have a problem with.
This may be an interesting ride....