This was P3P. Without legal backing, advertiser's will weasel out of any technical measure. You can even see this in the common practice of showing a app speci

This was P3P. Without legal backing, advertiser's will weasel out of any technical measure. You can even see this in the common practice of showing a app specific permission prompt ahead of browser/OS level prompts because they no that being rejected at the OS level removes their ability to prompt again later. Legal systems are not so willing to prescribe specific technical solutions to avoid the "oh, you had very specific rules about advertising on radio, but this is TV so we get a few years of free roaming before you can update the law" issue