It's not hard to hire people to write PR stuff. It's just unemployed english majors of which there are legions. There are no associated costs as the positions have no benefits and everyone works from home.
...and the interns get to say "I've written for New York Times" the next time they interview for a job. Everybody wins, as The Economist argued: http://www.economist.com/node/21528449
Although there are hidden costs even behind unpaid labor. Office space, HR costs (hiring isn't easy), training, etc, etc.