In a country with 25% Evangelicals and 23% Nones, is it surprising that public policy doesn't reflect the social teaching of Catholics (22%), especially since most Catholics are only vaguely familiar with the tradition and many actually disagree with it? Ask any US Catholic about Leo XIII and see if they mention Rerum Novarum (or can tell you who Leo was). 
Since so many Catholics voted for Mr. Trump in 2016, I think we have to acknowledge that Catholic Social Teaching has not been well explained by our leaders or well received by the people. The idea that Catholics would vote en masse against their perceived self-interests in order to promote the common good as defined in papal encyclicals -- well, it's hard to find instances of that happening in practice.