Microsoft gets the contracts because they do lots of lobbying (i.e. corruption), marketing to government, lock-in tactics that keep government agencies stuck on them, and probably some side deals with NSA since that stuff goes way back. It pays to pay off or help the right people. They pay you back. Then, the others are stuck on your stack due to bad decisions, don't want to admit it, and then sing praises of things they're forced to buy.