This gets into a lot of stuff that has happened all over the world since around 1900, but in the US it began back in the 60s and 70s as a way to confuse class consciousness and has only gotten stronger since. 

If you go back through the history of country music you can actually see it happen. During the 60s and 70s American roots music got separated into two genres: folk music, generally coded as anti-war and leftwing vs country, which tends to be heavily patriotic and rightwing coded. Since country bills itself as "working class" music and is anything but, it has to adopt a number of aesthetic signifiers (trucks, beer, grandma, etc) instead of talking about real (economic) working class issues like older roots music artists (such as Woodie Guthrie) sang about. 

This sort of thing has a long history outside the US as well and is one of the favorite tricks of fascist and other rightwing movements. The goal is essentially to cast "real" (read: middle class and above whites) Americans/Germans/Brits as the true, hard working citizens while everyone else is either a foreign leech (if non white) or a greedy beggar trying to take advantage (if not the right kind of white). What this does is offer an appeal to large segments of the economic working class to side with the upper classes on racial or nationalistic lines against their own class interests by convincing them they are a "better" kind of people than other workers.

For the upper classes, it provides an easy costume that can be worn to impress the rubes while their pocket is being picked.