apples and oranges. The 3 months of Showtime is just an incentive, they'll get you hooked on a show, at which point many people will get the actual subscription when the free trial runs out
Well, true... but it's still an incentive that is normally reserved for new customers. My point being that customer retention is something that companies take seriously.
It worked out well for me, since I had watched 4 seasons of a show via Netflix over the summer, and season 5 had just started (and is now over) on Showtime. When it expires, I won't miss it, but I thought it was a nice gesture.