Carolyn,
The subject by itself is endless, but :
1. No, you are not (unfortunately so..) missing anything and your observations are correct.  
2. The quality of the bulgarian education is long gone now, and whatever is left of it is mostly supported by volunteers like yourself. 
3. There are no opportunities in Bulgaria for well educated people.  By studying abroad, the bulgarians have an immediate access to real labor markets and farther development. Things they would not have while in Bulgaria.
-Adrian