As for post production welds outperforming robots. Well, I never said that. But any certified welder will tell you that if he does one weld correctly, he will do ALL his welds correctly. Hence that is why he is certified. As for very few welders doing that consistantly, well, hate to burst your bubble but if that is the case, all our highrises should be condemned because EVERY ONE of those welds HAS to be perfect. Same as all the pressure vessels. Hell, every propane tank or rail car, truck chassis etc HAS to be perfect. BTW: consistantly perfect welds are NOT that hard to do....
As for rolling death traps: That is why we have the certification process. The vehicles are inspected to insure they are safe. Now I will give you the fact that there are many dishonest mechanics around that will certify a vehicle that doesn't deserve it, thankfully anyone with any common sense wouldn't have their vehicle inspected by one of these.