It goes something like this:

(Client): I want to add a shopping cart to my site. I heard that xyz cart is free, can you add that for me?

(Developer): Sure! That looks easy.

In honour of the release of Drupal 8 here is a list of 8 of the best Drupal designs. I chose these designs because they truly display the power of Drupal. Anything can be achieved on this CMS.