Why are there no very low bids/very high asks on GDAX?
It appears that the GDAX main page only shows orders that are fairly close to the market price, probably to keep the user interface manageable.  You can see a wider range by increasing the aggregation.

You can't view the complete order book through the UI, as far as I can tell, but you can get it through the GDAX API.  If you fetch 
https://api.gdax.com/products/BTC-USD/book?level=3
you get all outstanding orders in JSON format.  There are asks as high as $9999999999 and bids as low as $0.01.