I think the interview by Derek Miles indirectly sums it up perfectly. The culture in the US is not set up to aid or help post collegiate vaulters.
http://www.youtube.com/watch?v=sKYRkTaFXD4Bottom line it takes time and many are not willing to take the time it takes and quit. Be patient and give the next generation a chance to come into their own. If you want to help throw them some prize money or appearance fees to come hang out at your club with your youth. As Derek stated the struggle becomes do I work or do I vault.
Everyone can keep preaching technique, technique... There is not a vaulter out there that wouldn't love to focus and train from the best of the best and learn. The reality is they can't afford to do it. Perfect example is a young lady who was thinking of moving into town made the comment to me, "I have learned more in 3 days than in 4 years of college." I had to watch her realize that sadly she may not be able to move to actually train (where do I live, where do I work, how do I pay bills, can I train and work 40 hours a week, can I find a job that will let me travel to compete, will there be enough money left over to eat, how can I pay you for your time). This is exactly why we have such a big gap right now. Let's address those issues as they are the real ones. Technical issues take care of themselves over time and have to do with more issues than just doing it.
Recently I have had some lengthy conversations about this sport with outsiders and most of them go why would anyone continue competing if there is no money. Find or ask anyone deep in debt how they feel every morning when they wake up? How much weight is on their shoulders each day worrying about how to pay this and that bill. Than think how can that kind of person train? Personally I wish more athletes would do what Derek did and tell people how it is. This sport is failing all over the world. That should be our #1 concern.
Non Americans think well its the USA it must be amazing to live and train. Track and Field here is so not important its worst ratings than figure skating, bowling and watching paint dry (nothing wrong with them either). Our culture is set up to care about basketball, football, baseball and other sports. You must first understand that.