I think this is because it is unlikely to ship with the wall charger for the lower trim models. Much like the Air, most people don’t use the charger and it’s more of a waste of space.
Maybe that’s just my opinion, but I didn’t even have it in my daily driver car and had to look for it in the other vehicles when heading to Arkansas the other week. Was nice to have it for a road trip so I could mooch off my friend laundry outlet instead of my free EA charging. (Also helped when everyone and their brother asked me for a high speed ride around the winding Ozark highways)