IE is a very bad browser to develop for. There are
whole sites devoted to enumerating it's CSS bugs, and more sites dedicated to
IE's JavaScript memory leak bugs. And there are at least 3 major browsers that anyone can use, for free, on Windows instead of IE:
There are little niche browsers out there, like
Flock (there are certainly other niche browsers, but I don't know about them).
And if you're gonna use IE, then at least upgrade to 7. IE 5, 5.5, and 6 are just awful.
Why don't designers and programmers just tell visitors: "look buddy, if you want to see this site, you're gonna need to ditch IE. That's life."
Because it takes balls to say something like that, and most companies don't have any. It's cheaper and easier to pay some poor schmuck big bucks to fix browser incompatibilities than it is to tell your customer that they have to take 10 minutes to install a better browser.
People like to think themselves compassionate and kind. Well, realize that by continuing to use old buggy browsers you are causing real pain and suffering for web developers. I don't see why some people would never wear fur but would continue to use IE 6.
[
Update: Alex commented that changing browsers is scary. She's right. So to make it less scary I suggest that people make Firefox look like IE 6, as described
here. Indeed, it would be in all web developers self-interest to make a neatly installable package that includes these changes.]