When you torque up a fastener into steel or aluminium it is a very known thing and has been done (literally) billions of times, so you know the likely result (ie. it will not come loose). When you make a carbon fibre structure and insert steel or aluminium components (or similar) for bolting to, you are stepping more into the unknown and relying maybe on aerospace experience. In this case a manufacturer would be wise to show caution and check that critical fasteners remain tight and that nothing is unexpectedly moving or yielding over time. Once the automotive industry has more experience of composite structures I'm sure they will be better able to predict the result and not need to check this sort of thing.