Not only that but the 12 Pro Max sells substantially better than the 12 Pro, according to the chart.

A smaller underpowered phone.

You aren't calculating the effect of phone size correctly.

Other than screen resolution and smaller battery (due to the size difference), the 12 mini and the 12 have the exact same specs.

You might be thinking of the iPhone SE, which is the budget offering that’s almost as small as the Mini and has lower-end specs.