Almost all advertising companies were gearing up to respect that, then IE10 violated the standard as in the RFC and set a default value for that header.

> Do Not Track option activated in my browser

1) "Incognito" mode.

2) "Clear browsing data".

> Seems like nobody cared about it

That is exactly my point: vast majority of users do not care much about removing their cookies.

If users do not really care -- why pollute UI of websites with questions that users do not care about?

Those things don't stop companies from collecting information on you. I wish that stuff was stored locally.

>Most websites and web services, including Google's, don't change their behavior when they receive a Do Not Track request. [1]

1. https://support.google.com/chrome/answer/2790761