I don’t think that it is “ludicrous” to miss school for a non-academic pursuit – many kids do it – but I do think that it is irrational to assume that the travel will necessarily be accommodated and supported. Basically, that’s a choice that parents and students make. My daughter did a foreign exchange and it negatively impacted her GPA & her course schedule. She was able to work things out well enough with the home school so that she graduated on time and she ended up doing well for college admissions – but some things couldn’t be fixed. She had a valuable experience that will stay with her for life - no question at all that it was a wonderful opportunity and far more meaningful than whatever high school AP classes she might have taken instead. But it was an eyes-open choice with the recognition that it would result in an overall weaker high school record. Being away quite simply meant that she couldn’t do some of the traditional high school academic things that were available to and expected of the kids who stuck around.