Hahaha
You're totally right, most of the countries don't have their own games. But some do, and since the overall sections are very broad like EU and NA, we use the TLD codes to separate the different versions, rather than have one for each country.
So [CA] is used to differentiate Canadian releases in the NA category. [IT] or [FR], for example, are used to separate the different French and Italian game variants out of the EU category. I'm not an expert on it, but that's how I've understood why it's done that way.