I think it's like he explained in the first blog post. Since people spend less time online in SA, they tend to search more for terms that they actually want to research - and not on frivolous everyday topics. So total searches tend to be less, and it is easier for a specific term to get a high normalized score in Google Trends.
In other countries that buy online a lot, the search term "psalms" will have to compete with terms like "xbox" or "hats" for example, so those countries won't feature as high for "psalms" as SA might. Not to mention that these are just the english speaking countries, which cuts out quite a bit

What is also interesting, is that Philippines also feature quite prominently with South Africa...