Bit of a tangent but Canadians should be ticking "Yes" for "are you authorized to work in the US?" because acquiring TN status does not require sponsorship from

Bit of a tangent but Canadians should be ticking "Yes" for "are you authorized to work in the US?" because acquiring TN status does not require sponsorship from the employer; the TN is explicitly non-immigrant intent. If a company prefers to hire an American over a Canadian, that's discrimination on the basis of citizenship, which is illegal.