Hep B can't be transmitted through casual contact but I know at least my state demands that school children have the vaccine.
The hepatitis you are vaccinated for can be caught by casual contact, bodily fluid contact, blood contact, and kids are pretty darn sloppy in school, share drinks, joints cigarettes, and punch each other in the nose.
Hepititus is a far more serious diease as well. HPV is not.
True, but it does have 'casual' causes, and is very infectious. According to WebMD, Hepatitis B is spread by infected blood and other bodily fluids such as semen, vaginal secretions, saliva, open sores, and breast milk.
At public school, there are always a plethora of kids with open sores, and of course, kids see no problem with sharing a cup or whatever so that saliva can be 'shared'.