They don't charge because a good number of people *won't* pay that $20/year. And...

		jedc on Aug 28, 2009 \| parent \| context \| favorite \| on: LinkedIn charges $250 a year to view users' full p... They don't charge because a good number of people won't pay that $20/year. And if those friends/colleagues/family don't pay and aren't on the site, it becomes less valuable for you. And then suddenly you won't pay the $20. :)