Why Can't we Print From Our Smart Phones?

Image credit: Databazaar blog

Now I know there are apps you can buy on the iOS App Store and in the Android Marketplace that will let you print from your phone, but why isn't it built into the operating system itself?  If smart phones are the next phase in evolution for computers, it should be a standard function.

Now honestly I admit, the need for me to print something from my phone doesn't popup very often, but when it does it becomes an issue.  Not enough of an issue to buy an app, but enough to make me wonder why this hasn't been solved by now.  I do have some theories why I think this is a feature that hasn't become a standard yet.  Hit the read link to see what they are.