Photo Sharing Website APIs. Why is Printing so Difficult?

Does everyone find it as annoying as I do that the big photo sharing websites don't have good printing interfaces, say Photoshop quality, and seem to be relying on pushing cusomters to photo printing companies for business. As a user of these sites, it seems to me that a lot user-value could be added in a straightforward way.

But first some background:

Comparison of Traffic on Photo-Sharing Sites

APIs
http://code.google.com/apis/picasaweb/developers_guide_protocol.html seems clean
http://www.flickr.com/services/api/
http://www.snapfish.com/
http://www.kodakgallery.com/Welcome.jsp
http://www.shutterfly.com/
Photo Sharing and Printing
http://www.pcworld.com/printable/article/id,127882/printable.html
http://gallery.menalto.com/node/954
Potential Back End
http://www.enomalism.com/features/next-generation/
Interface to Mobile Phones with Cameras
http://peterwilliams97.blogspot.com/search?q=mobile+phones


Potential Plugins
Printing to computer printers (instead of print shops)
Image filters
Image analysis
Photo organization
Making people more attractive which could also impact crime rates .
http://machine-learning.blogspot.com/2008/07/google-translation-flickr-api.html