This is not about a web browser coming with optional search engines, this is the UI which is also used to search for local files/programs, sending every query in plain text to Amazon unless (it's disabled).
https://bugs.launchpad.net/ubuntu/+sour ... ug/1054282
Obviously Unity / the "HUD" was designed with this kind of thing in mind - convince users they should be typing stuff in, instead of clicking on things - capture that data = $$$$
People excuse it with "oh well they need to make money, FOSS can't survive etc..." well it seems to have survived very well so far without Mr Shuttleworth's business model...