Those bits about the price in Canada feel like clickbait: technically possible, but with caveats learned only after clicking, like perhaps it's only experienced by people with non-Canadian SIMs who decide to use a terrible roaming plan instead of something better? But with the links being dead, this is just speculation -- not writing in this format (of third-party dependencies filling in what appear to be major gaps) would've been helpful to avoid such speculation in case I'm entirely off-base and that truly is the price of data somewhere.
I don't know about actual canadian prices, but I do visit canada periodically, and only once was I in a position to go through the complexity of acquiring a roaming SIM. My cost is 20¢ per megabyte.
The last time I was there for a week I made sure to exclusively use Firefox+NoScript and setup a number of large regions in google map caching - in past I also used Firefox data saver image option, but regrettably they removed that from the config (hm, I wonder if it's still available in about:config as a hidden option - shame they also blocked about:config unless you use a non-mozilla build)
(my suspicion is it was probably one of the many cool features lost in the rewrite)
There are still data limited cell plans in the US though. Quite a few sold by T-Mobile partner resellers as economy plans.
