That's interesting. You guys don't have a cafeteria where they serve lunch at school? All schools, I believe, in the US have a cafeteria where they cook lunch every day that you can buy. Eat at your own risk though. 14-15 year olds would be considered 9th graders, or freshmen. They are too young to drive so they can't leave anyway unless they ride with someone or walk.
In Australia, or at least my school and a fair few others you're not allowed to leave school for lunch without a note from your parents. Or, in year 12, if you have spares for the final two periods.
Of course, that's easily solved by simply walking off campus, or forging your parents signature. You have to be able to do both, though.
That was the same at my old school, but in most cases people would leave to go off and do...illegal stuff. A few incidents happened where the cops intervened and everyone involved, regardless of whether they actually did anything or if they were just there with the others, they got in major .
In Grades 11 & 12 we finished @ lunchtime (1.15) on Thursdays, and in Semester 2 on Wednesdays as well once the interschool sport finished.
i think in most schools in California, 1) the campus have marked boundaries which you can not go past during lunch, so some parts of the campus is off-limits, 2) in most high schools here, leaving campus for lunch is only allowed by upper-classmen (seniors, etc) and i think a document that is signed by your parents must be on file at the school, and those that return late to class from leaving campus for lunch have more severe punishments then others who are late to class, possibly loosing the privilege of leaving campus for lunch.
But at least my high school did not have metal detectors like some