There will obviously always be some cheating (and also some sloppy practice), and probably the only way to reduce it substantially would be to regulate it, and police the activity of testers.In other words if done by the book then it is all about trust there is nothing to stop a tester cheating.
If those who undertook EICRs knew that there was a significant risk that their EICRs would be subject to random checks (maybe by using 'set up' installations) and that they would 'lose their licence to undertake EICRs' if their reports were found to be seriously wrong (or plain fraudulent), then we might see an increase in conscientiousness on the part of the honest and a decrease in cheating amongst the dishonest. If it can be done with MOT tests, then it could be done with EICRs.
Kind Regards, John