Civics courses are and were little more than rote indoctrination in the status quo. It makes you appreciate the political system. (E.g., take them in the UK and you will learn how great monarchy is.) But our current education policy has less civics now.
I'm not sure if you're referencing the paper or not, but its conclusion lead me to a similar idea. The author points out that previously, higher education was mostly reserved for the elites of society and that its increasing prevalence among developed countries happened around the same time greater education began to gradually change from being correlated with greater trust in government to being correlated with less.
The obvious idea I had was that a greater amount of people were coming into contact with more information about the various failures their government (and every government) has. People are getting a "reverse civics" class now -- and in a way, ignorance was bliss.
Here's a link to a version that seems to have the correct graphs: http://sci-hub.cc/10.1080/03906700500038819
I found Figure 3 particularly striking. Education (pre-1950) used to be correlated with greater trust in government, now it's correlated with less.