Google isn't above doing things that harm people to make them more money. Like the steadily decreasing background contrast and lack of borders separating ads from search results. Older people are far less cognizant of borders and thus would click on ads thinking they're search results.
The difference is that the negative Microsoft news tends to float on top of sites like HN more than positive news, and the reverse is true for Google so this alters perceptions of people.
http://blumenthals.com/blog/2012/01/31/is-google-intentional...
They recently got rapped by the FTC for it.
http://wallstcheatsheet.com/stocks/ftc-googles-ad-practice-i...
The difference is that the negative Microsoft news tends to float on top of sites like HN more than positive news, and the reverse is true for Google so this alters perceptions of people.