A jaundiced view of a nebulous concept
My simplistic explanation for public v. private cloud computing is that cloud computing is an ideal mechanisms consolidating private information in the hands of those who govern, whilst transferring private funds (read peoples' taxes) to special interests with little or no visibility or accountability. Governments can operate at a loss, performance is not an consideration, and no one is accountable.
Private enterprises and individuals, who are accountable. are understandably more conservative. They hesitate yielding direct control of storage and control of their information (effectively, their lives) to something as nebulous as "the Cloud."
(THE Cloud is myth. What we have are scattered clouds. It seems that almost every other APP I get these days, comes with a feature encouraging me to upload data to cloud storage.)
No one thinks--much less talks--about the risks. The fact is that massively parallel data centers face serious technical challenges to reliability--challenges for which technical solutions are in short supply.
These are generally dismissed by hand waving references to redundancy, with no reference to the elephant in the parlor--communications bandwidth.
We live in interesting times.