• Books may cost money, but reading them is free. So, anyone with access to books (like, say, through local library or Project Gutenberg) is able to travel in these magical bookmobiles along the superhighways of the imagination.
• The speaker expresses this simple idea by saying that even the poorest person can take this kind of "Traverse," or journey, without ever being "oppressed" by having to stop at a tollbooth and pay.