On "html title tag" what do you want to know about it that the w3schools result at 1 doesn't give you? I know you may not like the site in general, but is there more to a title tag than that?
A better example is: "html iframe element". Go ahead and look. What's more interesting here is that if you modify this query to "html iframe element scripting" the top 3 results are now w3schools, one related to the <script> tag, while the relevant section header in MDN on scripting isn't even highlighted in the matching result from MDN. The word "scripting" does not even appear in the rendered DOM of the w3schools page for <iframe>.
At this point, it's pretty safe to say that there's a reason, distinct from content quality, why w3schools is always promoted over better sources of information. Popularity doesn't seem likely either (http://www.alexa.com/siteinfo/mozilla.org vs http://www.alexa.com/siteinfo/w3schools.com). The site is:
1. Covered in questionable and low quality ads.
2. Intentionally misleading in general but especially in name (w3schools is not affiliated with the W3C or any standards body).
3. Abusing its position (in both search rank and in its misleading name) to sell useless "certifications" that not one company in existence would take seriously.
Why doesn't Google consider this a scam and factor that into its search ranking?