ah very good point.
so maybe an investigation should take place, don't you think? to see if anything illegal has in-fact happened. Now being a civil matter in the first instance, the private company would have to fund the investigation themselves.
Upon paying a speeding ticket or even only receiving a notice, you are actually admitting there and then, that you are breaking a contract of the civil laws that govern the land right?
So you are basically agreeing to 'settle out of court' and on the spot or within a few weeks. (normally for a lesser charge)
So from a civil stand point, you only enter the contract once you accept that you have broken it.
If 4 people are sharing/registered to a single car, How would they prove who was driving on the day of the "incident". I'm guessing they couldn't easily prove it unless they had some pretty clear pictures, or unless someone would agree to 'settle out of court' by paying the fine. Naturally a domestic discussion would take place in the household and the 'Guilty' party be pressured by friends and family to pay the fine.
My point is most of the time these people, are relying on us to tell them truth about what happened or in this case just settle out of court quickly and quietly, (for them at least) but it often leaves a distressing trail for the household affected, and its threatening to get these letters etc.