Probably already been stated, but the other obvious reason is the truck stops where the aisles are too narrow. In my humble opinion, if the aisle is too narrow to 180 it's too narrow. I think that is what 65-70'? A little narrower can still make it work, but this stops with barely 50' and only a couple spots left? That's pretty tough after a long day.
What they could do, though most would likely ignore it, is put a sign up that says to please stack. Stacking (filling rows sequentially) would enable greater utilization of the spaces. In a more perfect world, "Stacking" and a sign for small lots or narrow isle lots to please stack could become a thibg.