It's all because the browser-based bespoke applications that form the basis of a lot of company's systems, were written for IE6 and now need to be substantially re-written before they'll work with any other browser. This is what happens when project managers swallow the sales spiel hook, line and sinker.
As a result, Government departments and many large corporations are now faced with a choice of either sanctioning very costly software development, or putting up with the consequences of continuing to ignore the problem in the hope that it might go away.
My guess is that the Government, for one, won't want to spend money they no longer have; and the reason I wake up screaming at night is that we haven't even begun to experience the absolute Hell On Earth this problem will eventually become before they finally decide to bite the bullet.
Worried now? You should be.