They pay to integrate with third party services via a bidding process.

> adds significant risk that the third-party changes their API, changes their feature-set in an incompatible way, goes out of business

All very unlikely to happen when dealing with a client the size of google.

> It's both cheaper and more convenient for the end-user if the search provider handles the mapping itself

added bonus, google gets to dominate mapping then jack up the cost 30x when they decide they want it to be a billion dollar business. LIke they did recently.