> The only benefit Canadians get compared to others is the opportunity to work for employers on TN status which is a temporary non-immigrant-intent work visa.

That doesn't strike me as "not at all" when the TN status is 1/ effectively a work visa, whether you like the strings attached or not, and 2/ a foot in the door that lets you move to a more permissive status down the line. A Waterloo or UofT grad can go from applying to a US job to their first day in a few weeks, and the only interaction they'll have with the immigration system will be getting asked for paperwork at the border. Compare that to a British or Japanese new grad, for whom there is essentially very few options unless they have excellent connections or that they display enough extraordinary abilities to be eligible for O-1.

Yup, such visas (going both ways) are based on the NAFTA/CUSMA agreement and probably live or die with that agreement. Uncertainty limits what businesses and people can/will do, and the sudden loss of work/residency permission would be really annoying for the families involved.