SMOC - Using your logic, that airliners are weaker as they are bigger, as opposed to the way aircraft are tested to withstand x loads at y speeds...then I will run with your premise and see how it Socratically follows out..
Two planes take off into turbulance..one is a biz jet, another is an airliner.
Both are flown 1kt below Va, both are getting slammed around, both crews are doing what they can to keep the rubber side down.
In the ensuing departure, airline test pilot A, steps on the right rudder as hard as he can, all the way to the stop, then the left, then the right..the tail comes off, they don parachutes and bail out.
In the ensuing departure, bizjet test pilot B, gives a Jean Claude Van Damme kick to the right rudder, then then left, then right. Flight procedes normaly.
According to your view of how aircraft are certified the bizjet is an inherently more robust aircraft.