Matt Rosof explains why Google does a lot of stuffing of their own products in their search

Regardless of whether Google faces new charges, the thing to keep in mind is that Google is a for-profit company. Its products have to be good, otherwise nobody will use them. But they also serve the larger business goals of the company.

Everybody knows and understands this. What people are not aware of is that Google puts their own products ahead of others, even if they are of inferior quality. If they would announce that “this search has been altered in order for us to diminish our competitors”, nobody would have a problem.

But Google tends not to respect the standards it imposes on everybody else. And that is nice when you got the search market in a 90% stranglehold, but it’s not a long term plan.