Not sure about your analysis regarding other countries, but there is one clear explanation for why ARs and not handguns.
Political calculus.
Trudeau is trying to secure his position around the urban populations of toronto and vancouver and montreal. 1 million handguns owned by roughly 300,000, living largely in cities, is a huge cost to pay for pandering to approximately 500,000 city dwellers that may actually be influenced by such a proposal. At 300,000, handgun owners represent a broad cross section of society.
75,000 ARs owned by probably less than 30,000 individual owners. Meaning a lot less votes to lose. ARs on average are more expensive than handguns. Ammo is more expensive. Accessories are more expensive. Ergo AR owners tend to be richer, and therefore older, and whiter, then your average handgun owner, and probably weren't going to vote liberal anyways. Meaning the Liberals aren't likely to lose many votes at all over an AR ban, but have the same potential to capture the 500k or so undecided or soft liberal supporters.
Further, this strategy of AR vs handgun is being carefully crafted to try to placate the 2 million PAL holders that there is a rational basis for taking ARs that does not apply to handguns, ie this nonsense about ARs being designed to engage human targets as quickly as possible, as if modern combat pistols aren't to engage human targets as quickly as possible.
It doesn't matter that the liberal proposal doesn't make any sense to us, cause we aren't the ones they are trying to convince with this proposal. Despite being utter nonsense, the people they are trying to convince with this don't know any more about guns, gun laws or gun violence than the liberals do.
Perhaps. Most of the people who neglected to comply last time did so out of ignorance. They simply didn't know. I still meet people who think their FAC is still valid. With registered restricted however, the RCMP and CFO will be sending letters to all of those people revoking their certificates and ordering surrender of the firearms. I suspect compliance among those people will be fairly high, while those with NR guns affected by any ban will likely just keep their heads down.