I believe that's because all online banks don't use SSL/HTTPS, but instead some different encryption standard, which is only available as an ActiveX plugin, i.e. Internet Explorer only.
This is not really a truely free market where people can change.
Another reason is the proliferation of pirated copies of Windows.
Life is extremely hard for Linux users. Less so for OS X, but occasionally you still need to dual boot.
In January 1999, RFC 2246 (128 bit SSL) was finalized and permitted for export, but by then SEED was already entrenched. It's only now that smartphones are starting to become popular that they're trying to change things: http://www.koreatimes.co.kr/www/news/tech/2010/09/133_73601....
You can read Gen Kanai's post about it on the Mozilla Asia blog for more info: http://blog.mozilla.com/gen/2007/02/27/the-cost-of-monocultu...
People from Mozilla China have recently pointed out to me the crypto-related issues in China. My understanding is that you can make Firefox do what you need for Chinese banking but it requires unintuitive configuration and/or hard-to-get drivers. I am hoping that sometime this year we will make improvements to make smartcards plug-and-play on platforms (like Windows) that support it. This will be a nice benefit not only for Chinese users, but also for any other smartcard users.
I don't know enough of the technical details to fully follow the discussion, but it looks like support might have been added to Firefox ("Status: RESOLVED FIXED"): https://bugzilla.mozilla.org/show_bug.cgi?id=478839
This commit definitely makes it look like something has happened: https://hg.mozilla.org/releases/mozilla-1.9.1/rev/653b75a8f4...
[1] http://gs.statcounter.com/#browser-IE-monthly-201010-201012-...
Since it became At Internet they stopped doing it this way though.
StatCounter shows a pretty steady decline of IE since July 2008 (that’s when their data starts), down to about 45% in March 2010 (that’s the month when the browser ballot came with a Windows update) from about 58% (that’s about 0.6% per month). Since March IE has lost 7.8 points (that’s about 0.8% per month). All that loss since March was at the expense of Chrome (Firefox and other browsers could merely hold their March level).
That decline was a bit more rapid than the past average, but that extended decline is nothing special and also not particularly steep (there have been eleven month of near constant decline between August 2008 and June 2009 at an average rate of about 1.1% per month).
Firefox had more than 36% of the browser share since December 2008. The browser ballot doesn’t seem to have helped it so at least Firefox is in the position it is without any help from the EU. Chrome might have been helped by the ballot but even that is doubtful. North America which didn’t get a browser ballot shows a similar rise of Chrome.
A superficial reading of the data doesn’t show any effects of the browser ballot. You might be able to tease effects out with more analysis but I would bet that those are miniscule.
http://gs.statcounter.com/#browser-DE-monthly-201010-201012-...
http://gs.statcounter.com/#browser-GB-monthly-201010-201012-...
Globally, IE is at insane levels in South Korea (94%) and China (90% of which IE6 is 54%), Firefox is doing well in the Philippines at 47% with Chrome following close behind at 34%.
I guess the key take away is, as usual, know your own market.
edit: I wish you could easily see the countries with IE above 50%, I was surprised to see that by these stats the US just dropped below this level, mostly thanks to a strong showing from Apple's Safari compared with the rest of the world.