Do you mean why "doesn't" the govt? Because it is easier to write programs for Windows than it is for the Mac? The only reason for owning a windows computer is because you use a program or programs that are only available on windows.
Apple made a big mistake back in the early years when it was the hot computer. They charged a lot of money for a development system (software and support) for a platform that was harder to program on than DOS. Microsoft was smarter, they gave it away for free and offered free support too.
Finally Apple now gives it away for free (since about 2001 or so I think), but they are playing catch up, big time. Now for the first time it is actually getting slightly easier to program Mac's than it is to program Windows.
After the US Army's website running on Windows NT was hacked by a teenager and defaced, they switched to Macintosh xServes running OS X Server.
Despite the fact that the Army website is the target of hundreds of attacks every day, not one has succeeded since the switch to Mac systems in 1999. And uptime for the site is running at 99.995 percent.
Says the officer in charge who made the switch to Macs:
I wanted high-speed systems that could handle any application we needed, keep the site available 24 hours a day, not be vulnerable to every passing virus, and fend off hackers without my staff having to spend all their time applying security patches .Other comments on the US Army's choice of Apple Macintosh computers for their website:
— Mark H. Wiggins, Lt. Col., U.S. Army, Ret. Former director, www.army.mil
The host Xserve and its backup are tied to an Xserve RAID storage system. Although the facility where www.army.mil resides already had a 200TB storage array, IT managers decided to go with Xserve RAID for the website because of its lower hardware and support costs. “The bang for the buck with Xserve RAID is fantastic,” site manager Cerniuk says. “And the performance is just outstanding.”
How many IT people does it take to run www.army.mil and its associated systems? Thanks to the simplicity and reliability of Xserve and Mac OS X Server, Cerniuk’s team consists of only three people including himself. As he notes proudly, “We have a small group that’s managing one of the largest sites in the world.”
And the switch to Apple solutions brought another benefit. “When we moved to a Mac OS — based system, we were able to focus less of our energy on security.” Now, instead of spending their time installing patches, Cerniuk’s staff is free to explore ways to make the site even more valuable to the Army community. In addition, the Mac systems are part of an overall multiplatform strategy that Cerniuk considers vitally important for any organization. “If you only have one type of system, you can be taken down by a single virus. Our diversity gives the Army better security.”
With the proven success of Mac systems at www.army.mil, Cerniuk often gets calls from other government webmasters considering a switch. What does he tell them? “Contact Apple, test it, and then deploy it.” And how has that advice been received? “We’ve converted some very staunch Windows folks.”