When these students go for tours with their families. parents will be with them and they will attend to all problems and kids will just accompany them. But when they go in a group of students of his school or college, they have to manage their activities on their own. So they will become more responsible.
But schools should not send only students. But enough teachers should accompany the students. That will make the students behave in a disciplined way. Generally. teachers will not say no to such tours if the management accepts the tour and ask the teachers to accompany the touring students. During my students days, I attended many scout camps and excursions to nearby good places.