In a job 20 years ago at a composite shop, we did strictly custom work for the military or aircraft industry. That work consisted of inlet ducts for the old U2 spy plane, then being used for photography purposes, Apache helicopter and some work for Boeing. Our shop got epoxy resin samples weekly that were tested for particular properties for our projects. This came to dozens of resins whose properties were then entered into a data base. Chemical engineers understand the resins at a molecular level and can taylor properties for specific purposes. My experience and that of the engineers is just as the Aussie in the video stated. Carbon composite can be very strong when carefully built but there is no way to tell in advance. In a shop environment every aspect of the process has to be monitored and tested. As a rudimentary example, has the resin/catalyst been accurately mixed and cured parts tested. How do we know?