Why is <META HTTP-EQUIV=“Content-Script-Type” …> mostly unused?

All web browsers that I've heard of will default to assuming type="text/javascript" on all <script> tags, and type="text/css" on <style> tags. (The only meaningful alternative I've heard of is VBScript for <script> tags in MSIE, which is heavily deprecated. There's no alternative to CSS.) In recognition of this, the HTML5 spec defines both attributes as being newly optional.

As such, there's no point in the Content-Script-Type and Content-Style-Type meta tags -- as far as I'm aware, they're ignored by most, if not all, browsers.

It's a shame that these settings have become deprecated with HTML5. Because, as nobody else seems to be mentioning, you can put default character set settings in there as well! Thus:

<meta http-equiv="Content-Script-Type" content="text/javascript; charset=UTF-8;"> <meta http-equiv="Content-Style-Type" content="text/css; charset=UTF-8;">

<meta http-equiv="Content-Style-Type" content="text/css; charset=UTF-8;">

The CSS meta is important for inline styles where we can't declare the type, so:

<span style="background:pink">

Speaking as a developer who just learned about these tags from your question, I'd say that it's the curse of the legacy browsers (I'm looking at you, IE6). Because when I learn about new tags, I usually continue not using them. I always assume browsers might not support any feature that I've never heard of, until I prove otherwise (which takes time), and since you have to program to the least common denominator (even if you "progressively enhance" later), that means, in this case, using the safer, more verbose method.

Having said that, I may actually give these a try. There's little risk, unless you're using content types other than text/javascript and text/css, since those have been the assumed defaults, like, forever. Indeed, as @duskwuff points out, there's probably no point in using either.

They are depreciated. Now, people use <script type='text/javascript> and <style type='text/css'>.