I'm not really serious about the idea, but the idea of taxing users of outdated software could lead to some pretty interesting applications.
I working for a large company (100,000+ employees) in the US and we are stuck with IE6. We cannot uninstall or upgrade it without admin rights, which 99% of employees do not have.
A small minority of tech-savvy employees use Chrome or Firefox, but this is heavily frowned upon. Once when my hard disk crashed, our internal tech support team tried to blame the fact that I use Firefox instead of IE6 as the reason.
Is the cost of supporting IE6 worth hanging on to those impressions/sales? That's a call you've got to make on a case-by-case basis.
http://www.troyhunt.com/2010/08/aye-pirates-be-reason-ie6-ju...
Interestingly, some specific countries (namely the Phillipines and Indonesia) have a much lower IE6 usage than their equally poor neighbours, due to a very high market share of Firefox.
In South Korea, for example, all payment gateways and government portals are required by law to have certain "security features", which can only be implemented as an ActiveX control. (Good luck with security!) That explains the 94%+ IE adoption rate. Also, all those ActiveX controls break every time a new version of IE comes out, so users are understandably reluctant to move away from IE6. In fact, I've heard rumors that the only reason IE8 still supports ActiveX is that the South Korean government specifically requested it.
Of course, China and India together totally skew the statistics. Each of them is bigger than everybody else combined.
Africa and Asia lead in IE6 by almost 25%. I was surprised, but it does make sense -- pirated XP comes with IE6, people can't use Windows Update, so they just stick with it.