Don't legal service centers need lawyer qualification?

No need.

The staff of the legal service office have no lawyer qualification and can only handle civil cases, not criminal cases. The staff of a law firm are qualified as lawyers and can handle all legal affairs.

The staff of the legal service office are not qualified as lawyers. They can only do some consulting, write documents and represent a small number of civil cases. It is very important that legal services cannot represent and defend criminal cases.