Don't like any of the results from the real web? Well how about these we created just for you.
(Consumer demand and boredom both being infinite is another thing working against it.)
If Getty et al aren't already spending money on that possibility, they probably should be.
Google could totally afford it, especially if the feature was hidden behind a button the user had to click, and not just run for every image search.
How does Adobe prevent Photoshop being used to draw offensive images? They don't... People understand that a tool can be used for good and bad.