I helped implement a consent tool in our SaaS product that has users from a lot of different regions, many of which are more technical/"developer persona", and the tool we use isn't shady (it depends on the region, but for example in Germany it is opt-in by default and the options are presented immediately rather than behind a modal).
During the initial stages we had worried that consent rates would be low, and while Germany was "low" at around 70-75%, we found that overall consent rates across all countries were 90%+ with exceptions for Germany, France, and a couple other European countries. This was consistent across both the application and our marketing website, and across 10s of 1000s of users.
So while I don't doubt that the author ran an experiment and got these results, I strongly disagree that you will get "only 9%". Specifically, these lines in the blog post:
> And if you give them an easy way to ignore your banner or to say no to be tracked, most of them will simply do that.
> Most web users will simply select “no to tracking” once in their browser and the browser will block all the trackers for them as they surf the web.
is not correct, at least from my experience, and it absolutely can't be used as a blanket statement like this. Of course my anecdote is, well, anecdotal, so take it with a grain of salt, but I don't think it's fair to say that users will simply reject it no matter what, and it really depends on both context and trust levels.