Vietnam is definitely an odd comparison. The country is like 100-150km wide for most of its length and if you look at a map of their towers it's basically a single line up most of the country:
https://www.cellmapper.net/map?MCC=4...apType=roadmap
And of course their telecommunications are largely state-owned so they can offer services in unprofitable areas, whereas Canada has an oligopoly. Just like Canada Post will deliver places where UPS and FedEx won't.