Do you mean the cars in the race or the guys in first cut scene...however, my first answer still works halfway, the player was there (present) and saw those guys/cars, and just dreamed he would race these...simple? EA just did that like that?
EDIT OLD POST BELOW
Because he obviously had the day dream as he was there and just dreamed that he would be racing...so he saw those people and just dreamed his imagination into the reality, crushed it together.Besides, I don't recognize the people in dream scenes that much, except the starter girl being also a 3d model for some races, the others must be some background characters.
But under hand I just believe they (EA) didn't pay attention to these details and reused the 3d models in scenes, I think those only appear in the background and they thought people wouldn't notice the happenings in the background - which is true, if you play thru the career you usually see each scene for one time, so you basically focuse on the scenery in front of you, not the blurry things behind.