[hartez]

I don't know that it's the _only_ reason. I'm guessing another big part of it is that government agency software projects routinely run way past due and over budget, and often end up going nowhere. e.g.,

http://mobile.businessweek.com/news/2012-02-24/nextgen-faa-c...

or

http://www.usatoday.com/tech/products/services/2010-10-21-fb...

"The IRS could trivially set up a website" - no, you or I could trivially set up a website. The IRS can't trivially do anything.