@fulano
How did you get that experience kc99. Or are you just guessing what elders think? I have been in hundreds of comittes, last years in appeals almost weekly, and never saw this attitude you mention here.
Years of experience as well. There are two parts to the post. Firstly there is the the context of the confession itself.
As I said, the reasons are many and complex however, in general, the individual will either be fessing up voluntarily before any knowledge of the sin is known by the elders or afterwards once confronted about a situation.
The reasons that someone would fess up to something not known again vary, but again can be broadly categorised - either the person is motivated by sincerity and a genuine desire to right a wrong or they have an agenda based around trying to avoid the worst consequences, playing the game so to speak.
In the former case, the sincere feelings come from the control through fear, obligation and guilt, placed on individuals as loyal followers of WT doctrine. I have no desire to go to fess up to the police about nicking a toy from a shop when I was boy but some Witnesses get so hung up about a past sin they feel they have to go a lay bare their guilt to someone they are told has spiritual oversight over them.
In the latter case of those confronted with a sin by the elders then the confession has it's own overtones. If an individual is trying to manifest "godly repentance" then the attitude in the JC is very different to one who does not really care and is simply going through the motions before the inevitable.
The second part of the post relates to the attitude of the elders to judicial matters. To be fair I was making some generalisations but they do reflect experience.
If someone gets a fit of the guilts and comes to an elder years down the line, it's generally a PITA to have to consider forming a JC. As was point out earlier in thread (by yourself I think) the Shepherd book details a get of of jail free card for elders and the same is applied to R&F. If you are/were an elder, would you form a JC if a married couple came to you after 5 years to say they had sex a couple of times before marriage? Even if you did the consequences were unlikely to be disfellowshipping, private reproof at most but even that is unlikely if sufficient time has passed. How many elders would simply say to the couple - "don't tell anyone else, it doesn't really matter now, just pray it away". If they've told two elders then it becomes a hassle as it needs more officialdom.
As for JCs about the sexual misdemeanours of young women - you and I both know the detail that elders go into and how unnecessary it invariably is. You and I also both know that there are ones on the BoE only too ready to jump in with both feet into those cases.