Major inspections became a bore when all aluminium aeroplanes, (sorry airplanes for the spellchecker), became popular in Australia. Austers needed the fabric looked at and wood in the wings problematic. In tube fuselage aeroplanes, (sorry airplanes), rust was a problem also. Today modern fabrics repel even the best testing punches and there are inspection ports everywhere on Cessna's and Piper's. Be this as it may, the modern engineer just isn't up to scratch in inspections and many "modern" aeroplanes have been found with cut and broken cables, corroded brackets, illegal fuel systems and a plethora of other small things like delaminating skins.
The engineer who did a major did the work. Schedule 4-5 just let them off the hook and the lawyers entered the business over duty of care problems.
The main point these days is some engineers just can't do anything unless someone tells them to do it or it's written in the reg's. Can't bother doing what needs to be done in the name of common sense and a mindset of demarcation if they do something the reg's don't tell them they don't have to do.
The poor bloody owner usually cops it in the neck either way.