Entertainment is easier to comprehend then politics. It easier to comprehend and get angry over X actor being a douche and cheating on his wife then it is to understand what it will mean when the 2014 provisions of the health care reform bill kick in.
Again, it's a problem of too much work, too little energy. You spend what little time/energy you have for maximum benefit, so if you want to be angry about something you pick something petty and easy to grasp.
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