If airlines are going to mine data from a captive audience several thousand feet in the air then they need to make a bigger deal of noting it. Much like the safety demonstration, before take off they should include a brief statement and have a Q & A sheet in the seat back. In this day and age protecting personal information is a touchy subject and not everyone is aware of that. You would think with the negative press for airlines these days and the huge debacles of cyber attacks and information leaks that airlines would be a bit more transparent on this practice.