The problems with a closed source blackbox system always show it's face. The string entered into a search bar is only a very small part of your search.
The rest happens by watching your browsing habbits when other sites install tracking code which phones home and keeps a running tab on you. Most of this tracking code by all accounts are trojan horses. Most web developers probably aren't even aware of what they are participating in when they install such things.
If we could see all the information Google uses to find our results, many would probably be appalled. If you wanted a giant Advanced Search page that let you tweak your settings such as age, gender, browing habits, then getting a job at Google as an analyst is probably what you want. Openness and transparency would make the clean and friendly homepage at Google look a lot uglier and intimidating to the end users.
We need to liberate search through open source. However, the framers of such must be careful to not create some monster like Bitcoin that allows all to see all transactions. I sometimes wonder where coders with no "feel" for security earn their wings.