Why is there so much interest in probation today? How does the use of probation affect the corrections system? Why is it used so extensively?

Because a probation officer is a interesting job, and many teens and young adults are committing crimes worthy of probation. Probation makes it so that, either A) you don't have to serve time or B) to keep you out of trouble after serving time. Its used so extensively, because it shows good results, and often always showing up with positive reply.