I can guarantee that there are many people who have no past trauma who have addiction. I can't say exactly how common it is (it may be a minority for all I know), but I know for a fact that they are there.
I’m sure there are some of them out there. The world is a big place. My point is, the vast majority of serious cases can be traced to developmental trauma.
Let me qualify that: every single case I have personally encountered, which is on the order of a dozen, can be traced to trauma. I’m making an educated guess about the wider prevalence. Getting societal scale data is practically impossible for many reasons including privacy.
However, for those looking for some data points, I’m sure Gabor Mate’s book mentioned in the original article is full of examples. The most convincing academic references I am aware of at this time is are Dr. Bessel van der Kolk (“The Body Keeps the Score”, focused on PTSD) and Christine Courtois’s books including “Treatment of Complex Trauma“ and “Healing the Incest Wound”, both of which cite a large amount of research literature.