Ah, I got confused, that was the one from 6 days ago.
https://news.ycombinator.com/item?id=27763164
125USD per GB. Compared to 14EUR per GB on this chart.
But I think you were on the right track, possibly most people have low-end plans so total revenue skews towards low end plans? But you can definitely get data much cheaper than 14EUR per GB.
You can get data at theoretically 0$/GB if you get an ungodly expensive truly unlimited plan, so the marginal cost isn't accurate, we have to be at or near the average, and most plans are going to be lower end.