Yahoo's goal with BOSS is to fragment the search market; Google is so far ahead that Yahoo knows they can't compete head-on.
Google doesn't want the search market to be fragmented; they want to dominate the market. I think that's why Google doesn't have a good search API offering.
Re:Google Web spam - Gabriel Weinberg's Blog
by moultano on Tuesday July 27, 2010 @07:46PM
(#1553101)
The actual reason for this is that Google is extremely (unreasonably?) paranoid about leaking how we do things to our competitors.
I think DDG is a great example of why Google doesn't have a BOSS-like API. It seems pretty clear that DDG is violating the TOS of the Yahoo API by mixing search results. Yahoo seems to be looking the other way (for now), but you can bet that Google would be less forgiving.
There's not a search engine out there that wants to allow you to muck with their relevance algorithm by changing the results, and Google has more to lose from DDG-like activity than it might gain.
It seems the Google search APIs have actually gone backwards over the last few years.