The legislation has been watered down by lobbying of the trillion-dollar tracking industry.
The industry knows ~nobody wants to be tracked, so they don't want to let tracking preferences to be easy to express. They want cookie notices to be annoying to make people associate privacy with a bureaucratic nonsense, and stop demanding to have privacy.
It even got decent implementation in Internet Explorer, but Google has been deliberately sending a junk P3P header to bypass it.
It has been tried again with a very simple DNT spec. Support for it (that barely existed anyway) collapsed after Microsoft decided to make Do-Not-Track on by default in Edge.
The industry knows ~nobody wants to be tracked, so they don't want to let tracking preferences to be easy to express. They want cookie notices to be annoying to make people associate privacy with a bureaucratic nonsense, and stop demanding to have privacy.
There was P3P spec in 2002: https://www.w3.org/TR/P3P/
It even got decent implementation in Internet Explorer, but Google has been deliberately sending a junk P3P header to bypass it.
It has been tried again with a very simple DNT spec. Support for it (that barely existed anyway) collapsed after Microsoft decided to make Do-Not-Track on by default in Edge.