Your first sentence here is most interesting to me. This is an aspect of car culture that's sometimes overlooked, but what it does is infantilize adolescents and provide an arbitrary blocker to normal human behavior (e.g. shopping, visiting cafes alone, etc) until the child is old enough to drive to those places. A kid in Manhattan is in society and has access to everything his parents do. A kid in the suburbs is outside society, in some very meaningful sense. His access to the broader culture is mediated through television, perhaps, but he's not actually there. He visits society when his parents feel like driving him there. [0]
Who is surprised, then, that the car represents freedom to so many of these kids? Where I grew up, a car was needed for everything, which meant that I had almost no access to the normal world at age 15 and almost unlimited access on my 16th birthday.
Like a fish who doesn't know what water is, most Americans don't even realize that car culture is all around them. And an appreciation for the status quo is baked in very early. The car is simply how you get places. How could it be any other way?
[0] I think this is actually really important. A twelve-year-old should be able to pick up some groceries, mail a letter, grab a bite to eat at a lunch counter, and so on, but these basic acts of socialization are completely alien to suburban kids.