Consider yourself lucky. I'm guessing it's because of location. A quick search for "Google Amp" had this result near the top (an Amp version of a tech crunch article). If you open it on a computer it just redirects to techcrunch.com, but on a phone it should stay on the google domain and have a little top bar added (unless it redirects you past due to region?).
https://www.google.com/amp/s/techcrunch.com/2018/02/13/amp-f...