Would you like all your neighbors to know what porn you look at while you masturbate? How about your employer? I mean specific pictures, how often and long you looked at each. How about every comment you've ever made on a forum. How about private conversations you've had with friends, lovers, or coworkers. Everything you've ever purchased on the internet. Everything video you've rented/streamed. All of it available and searchable to all your family, neighbors, friends, and employer. Most people don't consider this when they're told everything they're doing is logged. If this was explained to them, I think it's more likely that 99.999% do actually care about privacy and the .001% are just freaky exhibitionists who want their life on display.
