It's more of a problem with IE being the most annoying browser to develop for than developers themselves. Developers are using the standards. The problem is that IE hasn't caught up to the new standards. While other browsers have near full HTML5 support, IE barely supports anything. Due to this, a lot of developers have disregarded IE support. If it works, great. If not, hurry up Microsoft and add support for the things we're using that work in every other browser. That's kind of the mindset we have regarding IE.
*sigh* There has always been a problem with some developers and discipline, code management, version control, documentation, and knowing when to use something in production vs development. So called
web developers seems to have an abnormally high number of these types of developers, though.
Those developers are coding to
webkit not the standards. Heck HTML5 hasn't been standardized - by the strictest sense it shouldn't even be used in production sites
at all. But there is a part of the standard that has somewhat stabilized and might be
ok to use under strict control and with the understanding that it very much is use at your own risk.
But many Web Developers don't want to understand this. I doubt many of them really understand how HTML, JavaScript, and CSS actually work and interact with each other. I just see way to many that coopt some lame open source library and then complain when it doesn't work perfectly in their environment.
In my experience, if you stick to published standards wherever possible (and it is possible a lot of places, HTML4 is rather capable) and only deviate in extreme cases into the experimental with a good fallback your websites will largely work across browsers the first time and every time. It's programming, not rocket science.