It has to do with where in the barrel stroke the cams for cocking are actuated. Different mechanical advantages at different places in the arc.
Many shotgun brands could revisit their cocking systems and make them easier. And their customers happier.

But I believe it's a "Isn't broke, don't fix it" carryover from long ago.

I think cocking shouldn't commence until the action is mostly open. Many firms disagree.

Out there doing it best I can.