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Stop Using Your Face or Thumb to Unlock Your Phone
(gizmodo.com)
This is a most excellent place for technology news and articles.
Oh, in day to day usage I agree with you: we're all one little uninteresting datapoint in a whole lot of datapoints and there are plenty of other ways in which we are tracked.
However if you're part of a Political Party or Movement and/or attend demonstrations, it's probably wiser to leave the phone at home, if only because that makes you stand out as a much more interesting datapoint than average.