Barriers to Adoption of Precision Ag

I have been following a discussion on Linkin about barriers to adopting precision agriculture.  First let me say that precision ag has been around since the beginning of farming.  Farmers have always known that some soils are more productive than others.  As scale of farming got bigger, that fact was ignored.  Now we have the ability to treat unique areas in unique ways using electronic guidance systems.  So why isn't everyone using modern precision techniques.  I am sure there are lots of reasons, but the group seemed to think the following are barriers:

• Customer support
• Ease of use
• Cost
• Cross compatibility issues
• Economic gain not  apparent
• Lack of knowledge about what is needed to adopt
• Lack of good advice