Behavior issues are often from needs not being met. The smaller class size lets me meet those needs. Classroom management is easier. It's simply more peaceful. Since there are less students, we can spend more time with each parent.
Less time is spent on grading, report comments, etc.
There are less desks in the room and there is more space to have groups. There is less out of pocket expenses for the teacher. It is less stressful for the teacher and the student. Behavior issues decline thus leaving more time for on task instruction.