well it works in the transformers world. Believable reality is relative and all based within the setting/plot of the movie. Transformers is a sci fi movie, they transform cuz they are alien robots, thus its justified. Just like Superman has powers because hes an alien.
Bruce Willis riding on a jet = because that movie is set up to take place in the real world and bruce plays a real guy. Hes no bionic commando or alien badass. So within the realm of the movie, that was a bit more ridiculous