I try to stay out of this BS these days, but ill say this anyways:
The problem with this "abstinence" idea is that if you live in an area where society largely expects it of you (the teen), you won't dare risk going to buy condoms for fear of being seen by someone you know, and/or avoiding the judgement of even strangers (cashier/anyone else in the store).
So then "in the heat" of it, as much as they may try and want to abstain... IF it happens, well, your kid who's been preached and guilted to abstain won't have any protection for that slip-up. You're indirectly causing the risk problems that come from unprotected teen sex.
Heck they don't even need to be in an area that's heavily promoting abstinence, they just have to be part of a group, such as a church. That's enough to create this guilt and they won't dare attempt to get protection. The decision and act of publicly buying a condom would be like crossing the line and making that decision to have sex (and announcing to the world--well, the world at the store) so they won't do it. It's way more responsible to get "insurance", and still preaching for them to wait as long as possible. But the abstinence camp doesn't see it that way. Give out free condoms and it's "Oh noes! That gives them permission!". No it doesn't. No more than buying car insurance tells people to go out and wreck their cars.