The thing is, in California, there are so many mother fucking people in jail. Judges hate putting people in jail, especially for drug stuff. Once
Courtney seemed to be clean, there was no point in making a jail more crowded, since all of her violations stemmed from her crack-whore-itude, which she took care of by going to rehab.
I think it's not surprising at all that
Courtney didn't get jail time and Paris did. Paris violated a judges order -- and not simply because she's some drug addict with poor judgment -- she just didn't want to follow it and got caught.