It's not just an issue regarding DBAs. There are several closely related and legitimate job roles that involve using SQL and databases (reporting, programmer analyst, etc.), and it's amazing how hard it is to find people for those jobs as well.
I just think there aren't enough people training on and learning database theory and real-world SQL and database tasks. Heck, most days I find another area of SQL that I don't know as well as I should, and then I have to try to learn it while I am also responsible for all of my other work.
And that's not even counting the difficulty some people and organizations have in understanding what a DBA is, or why one is even needed.
So along with those (including those in the "how hard can databases be" crowd :w00t
who deliberately fudge resumes in order to make it seem like they have DBA experience, there are many others who are honest and well-intentioned, but who may not realize the scale of the DBA job. So they may show up and disappoint you if you're hiring, or they may be scared off when they read a genuine DBA job description.
There should really be a DBA major in colleges, or at least a comprehensive computer science minor that includes realistic DBA tasks - SQL with procedures and error handling, performance tuning, db theory and applications, backups, recovery (including testing backups), and so on. I know there are specific CS courses offered, but it really is a field unto itself once people realize what is involved.
And ironically, most other professionals depend on DBAs - businesspeople, doctors, lawyers, professors, police officers, pro athletes, and so on. And not just in the way that lots of people depend on certain basic items (paper, fabric, food), but in a way that requires someone with a lot of ability and knowledge of databases to keep things running for that particular organization or even that particular location. I don't intend to disparage providers of paper, fabric, and food, of course, since those are staples of civilization. I just mean that needs that a DBA serves are of a different and more specialized category, yet they paradoxically involve a multitude of disciplines - the db products themselves, programming, networking, security, hardware, etc.
Sorry, this reply went off track. :-) But I do think it is relevant to understand what might be affecting the size and quality of the candidate pool.
Just my two cents....
A SQL query walks into a bar and sees two tables. He walks up to them and says Can I join you?