The script you read was a very early version, and as the screen writers said on yahoo movies that version of the script was completely reworked and in no way reflects the movie that was filmed. They aslo stated that the ratio of transformer screen time to human screen time is now 50-50. And they said that that was a rough write up, and that 4 pages of dialogue in a script of theirs translates to maybe 30 seconds on screnn and that when they wrote the action scenes they were very vague about them and that the action was expanded a lot during filming. In the video they explain there motives behind changing bumblebee into a camero instead of leaving him a VW bug.

Here is the link to the interview on Yahoo Movies:Transormer Undisguised: An Interview With The Screen Writers

Scroll down the bottom of the page, and you will see the video it is #8 and it is titled Transformers Undisguised.