So maybe the text in the UI jut needs to be changed to be more accurate. Instead of "Do Not Track", something along the lines of "Request No Tracking Across Sites" or "Request No Cross-Site Tracking". This clarifies that it isn't the browser stopping tracking, it is the browser asking the sites not to, which they may or may not implement. It also clarifies that what is being requested not to happen is using the same identifier across sites and between different parties.
On an unrelated note, I'm really impressed with the Persona login on that site. When I first saw it I thought, oh no, not another username and password. Why can't they just use social login where I already have accounts? But all I had to enter was my gmail address, approve the usage, and I was done. No extra username and password even though I've never used Persona before. No need to confirm an email. It worked out really well.
On an unrelated note, I'm really impressed with the Persona login on that site. When I first saw it I thought, oh no, not another username and password. Why can't they just use social login where I already have accounts? But all I had to enter was my gmail address, approve the usage, and I was done. No extra username and password even though I've never used Persona before. No need to confirm an email. It worked out really well.