Not to defend Washington too much, but things like GIS mapping data while present in multiple agencies, isn't likely the same, and you very likely can't easily or completely fill 1 agency's data need's with another agency's data.
What should be done is to actually see what uses and needs each agency has first, and determine if those are true needs and uses. If so, then they need to determine if and how another set of data can be used to replace their data. Sometimes replacing your data source with another source is possible, but the interface to the new source could be too retarded and expensive to implement.
The even funnier part is that in many cases 10 times as much money will be spent talking about whether or not certain data is necessary and what interface to use to get the data, than it would to actually implement a solution. If nothing else, proper paperwork and change request forms need to be filed and approved.
But I don't trust our lawmakers, or even the heads of the agencies to get that right either.
It's a cluster!@#$, and some people need to be monkey stomped.