Half the problem is the JAA law exams, in the ATPL (or CPL) series. There is very little in the syllabus relating to what is required in a commercial operation before getting airborne.
The CAA needs to sort out the training system so pilots know about requirements for experience, training and paperwork in the office and on the aircraft for a single-crew operation. Then they could start to hold pilots responsible for making sure the paperwork is correct. Until they require pilots to know what the correct system looks like then pilots are going to work for dodgy operators. Most will not know they're breaking the rules, and if they do know they can plead ignorrance.
Incidentally it would make my job as a line training captain easier!