Canadians were pretty freaked out in 2020 by how many COVID deaths occurred in the USA, and I think that has strongly biased their views on whether or not to open the border to Americans. A small number of American residents were highlighted in the Canadian media when they flouted the COVID rules in Canada, which did not help, as biased as those reports were. Thus, the Canadian politicians must view opening the border as political suicide until both countries have achieved at least 70% vaccination rates.
Unfortunately, though, the European Union and the USA have been limiting vaccine exports to other countries, including Canada, which means that the general population in Canada won't be fully vaccinated (i.e., two shots for Pfizer, Moderna, AstraZeneca vaccines) until probably fall 2021. Only the first shot will be completed in June. Until then, I can't imagine the borders will reopen before then, which hurts both our countries. Stay strong and be safe everyone.