Uh huh. From the paper reference:
> The study was carried out amongst a demographically
representative sample of the online population aged
16-64 in the following territories: Argentina, Australia,
Brazil, Canada, France, Germany, Italy, Japan, Mexico,
Netherlands, New Zealand, Poland, Russia, South Africa,
South Korea, Spain, Sweden, United Kingdom and
United States. The study was also conducted in China
and India but results from these two countries are not
included in “global” figures due to the size and nature of
these markets. In total, 43,000 internet users were surveyed with
higher numbers of respondents in larger markets.
They literally just surveyed first world users and made no effort to control for class or other confounding factors that influence musical taste. This pretty much only tells us what first-world city-dwellers like, not the world generally. We're no closer to knowing whether country music is truly the most commercially successful music genre worldwide, but neither are we any closer to disproving it.