AFAIK it all boils down to the fact that during embryonal development our cells, which at that point were just a blob of undifferentiated autonomous chemical machines, somehow managed to unanimously agree upon the cardinal directions (up-down, left-right, front-back) for future development - and thanks to this, we don’t have toes growing out of our ears.
Someone was probably born with toes on their head in the past and life didn’t go so well that they could have children that also survived. This is why our DNA doesn’t have instructions for growing toes on our head.