The decepticons are more numerous, and they can fly so they have every tactical advantage and somehow lose every time...
Yeah, what the fuck is up with that? Here you have a race of intelligent robot aliens, and it turns out that all the ones that are capable of flight are evil? How does that make any sense? It's even stupider because in the Bay movie, he shows them transforming into shit based on what they see. All the good guys become cars or trucks; the bad guys have a couple of land vehicles as well, but also some fighter jets and a chopper. What the fuck is that all about? Is there some agreement on Cybertron that anything that flies is evil?
Bot 1: I want to be a racecar!
Optimus: OK, you're a good guy.
Bot 2: I'ma be an airplane!
Optimus: ROBOTS ARE NOT MEANT TO FLY. I CAST THEE OUT!
Or did the good robots just have the misfortune of crashing in a suburban auto-mall as opposed to a military base. And why couldn't they just change later? Bumblebee did. You're telling me Optimus couldn't realize that maybe a semi truck wasn't the ideal vehicle to go after an F-14? If I were him, I'd start telling the autobots to start transforming into something a little more battle-ready than a Camaro. Clearly, he has no business leading troops into battle if he thinks that a Pontiac Solstice is a good match against a tank.