I think sometimes the factory can be conservative with the touch point (e.g. not really touching) meaning you end up grinding much lower on the grind scale. just remember when recalibrating to find the lowest touch point out of 3 positions, it must be on an absolutely clean grinder.
Another thing to remember is a feature of lower burr speeds, which reduces fines. Much more of the grinding is being done by the burrs and less by the coffee milling itself. This is akin to throwing 3 or 4 beans at a time into a single dose grinder and wondering why you get a gusher at what is normally an espresso setting when you put 18g in all at once. So the burrs have to be closer together (in micron) than a single doser running at 1350 rpm.