Yes, very much so. There are many positions in the church which do not pay, but youth directing/ Sunday school teaching does pay. At the few churches I have volunteered in the teacher has a few volunteer assistants (I have been one.) The youth are not neglected at all - in fact, I'd say they spend more time on youth than elderly people in my church.
Most teachers I know have a degree or certificate in Religious Education. I have a minor in Religious Ed, but I'm not as qualified as the current teachers are. It's more than just having the knowledge, though, as it's mostly about whether or not the teacher's goals line up with the church's goals. The teacher must be an example of Christian values, yet strict enough to control the classroom.
Good question =)