I did a little research of sex offenders in my area. After my research, in my opinion the most glaring issues are with the prosecutors and judges. Apparently, first degree rape is a 10 year deferred sentence in Oklahoma (tongue in cheek but that seems to be the normal result of the court cases I looked at). Assault with intent to commit lewd molestation will get you a 5 year deferred, and then when you reoffend with the exact same offense--they throw the book at you with 1.5 years, but you will only serve 8 months.
Prosecutors, at least in my area, appear scared to go to trial. They plead everything and 90% are no jail time (even including violent sex offenses). Judges should not accept these pleas if it is not in the best interest of upholding the law.