Got the email today and enrolled via:

https://www.milesforopinions.com/signup

It doesn't seem to be targeted, but I have no way of knowing what databases they might have checked me against. So far I've tried one questionnaire. Got kicked out after one quick question (for being semi-retired), got 3 miles. Not a lot of miles, but not a lot of time wasted to get them. It's not like they told me after I wasted ten minutes on 50 questions.

Will probably report on more experiences later.