Google say they are reluctant to track too much user behaviour when it comes to advertising:
” Susan Wojcicki, Google vice president of product management for advertising, said on Tuesday Google was shying away from the industry race to deliver tools for advertisers that stitch together a user’s various online actions into one profile“
Perhaps they’re trying to avoid mounting concerns around data privacy, which could potentially affect their text link selling business.
“Google’s planned acquisition of advertising tools supplier DoubleClick Inc. and the growing level of integration between its various services have raised concerns among privacy advocates over the potential to abuse its growing power”.
Or maybe past searches just don’t reveal that much about a users needs in the present.
” Google has been testing for several weeks a new advertising feature that delivers ads based not simply on a specific search term, but also on the immediately previous search, she said.”