I think as written, Wally and Clara are good solid blue collar people who value work, respect, discipline and what they perceive as middle class values. In other words, their views are a bit parochial as they never had the experience of college or of travel. Zach is the star athlete and they cannot see anything that distracts him from that as having any worth or value. That he has defied them and continues to do so, rankles and is not something that appreciate as normal for teenagers, at least not one that they raised....