Because many backward-thinking school administrations, the ones where funDUHmentalist christians dominate the school boards, only approve the failed and useless abstinence-ONLY sex ed programs. They have the moronic notion that giving teens the FACTS about sex and how pregnancy happens is bad. That sets the stage for failure before the program has even started.Nonsense.
Sex education and easy access to birth control should drastically reduce the necessity for abortion.. in theory.
So why doesn't it..?
When you have idiots who advocate the "just say no" party line, without explaining to teens WHY they're better off avoiding all kinds of sexual activity in middle/high school, you have a lot of ignorant teens getting either bad information or no information at all. When teens have sex and are ignorant on how easily unwanted pregnancy (and STDs) can happen, you have more teens getting pregnant, causing pregnancies, or worse getting STDs.