Whether it's "par for the course" or not, this requires us to trust that every immigration officer in service is enough of an expert in every field of endeavor

Whether it's "par for the course" or not, this requires us to trust that every immigration officer in service is enough of an expert in every field of endeavor to A) come up with relevant questions and B) judge quality of answers. The likelihood of that being true is incredibly low. What's worse, we know that typically people specialize within fields; a kernel hacker probably knows nothing whatsoever about using Ruby on Rails, but that might be the question the border agent googles up (or the web dev might get asked about kernel APIs). Plus: making excuses for this makes you complicit in whatever evil it begets, so maybe you should stop making excuses for it.