If this the case, why majority of air lined do not use Russian made aircrafts?
Safety has nothing to do with government. It is as good as safety protocols and rigorousness of safety clearance process. In all cases of space shuttle disasters blame is on government not contractors who made the shuttle.
The NASA management decided that Discovery was safe to launch not engineers. With Columbia it was similar. There was no inherent problem with design of the shuttle that caused disintegration during reentry.