That, and it's very hard to plan for a "logical" approach to sex, seeing as how sex hormones switch the thinking portion of our brains off (especially in the presence of that wonderful social lubricant alcohol).
My frank opinion, if we had open and honest discussions on birth control with young people, make birth control pills over the counter, hand out condoms like candy, that abortions rates would probably go down.
There are convenience stores in southwest Louisiana where condoms are kept on the counter in a big plastic fish bowl. While buying a coke or chips,,, whatever, the customer can grab a handful of condoms free of charge. Someone from the local health department keeps the bowls full.
That is an honest and open approach to birth control.
One of the problems is women have to jump through hoops to obtain birth control. Women have to get a pap smear, get a prescription, get the prescription filled, then wait a month for the pill to take effect. Some doctors will hand out pills at the visit.
But even if birth control was on demand, would people use it. And I think that is one of the big questions about curbing abortion rates.
There are lot of people out there who say, screw it, I will worry about it later.