Blaster: We're outgunned, man! We don't have a chance.
Kup: Boy, that's what makes life interesting.
Rodimus Prime: Or over.
Ironhide: What did you do to Gears? You turned him - nice.
Rodimus Prime: Last big party of the summer, folks! Let's go out with a bang.
Ultra Magnus: Just once, couldn't your attitude reflect the gravity of the situation?
Rodimus Prime: Not if I can help it.
Answer: This was actually one of many errors in Transformers, the Constructicons MUST have been built on Cybertron, the only transformers genuinely built on earth were the dinobots, reason being Vector Sigma has to give personalities to each and every robot, else they end up like the dinobots, very simple and dumb. For reference watch the episode "The Key to Vector Sigma" which introduces the Stunticons and Arielbots - both Megatron and Optimus Prime have to go to Vector Sigma to get decent personality traits installed, prior to this the new robots are controlled by remote controllers and have no AI.