Cybertronian Alt-Modes: Who the hell is supposed to ride in them??

I was thinking about something today while paying around the The Fallen's figure...He has an old-school Cybertronian alt-mode (as in, not an earth-based alt-mode) but he has a cockpit designed for a human-sized pilot...
What?
Nearly all of the Cybertronian vehicles from other lines and continuities (such as War Within, for example) have doors and seats and looks as though they are meant to be driven by a smaller person...
So who exactly is supposed to pretend to drive them??
I mean it makes sense that Optimus Prime as an Earth Truck has seats and a windhield and doors because he's in DISGUISE and earth vehicles have those things because HUMANS drive them...But why would his cybertronian alt-mode have them?? As far as I know, the only inhabitants of Cybertron are TRANSFORMERS...
It doesn't really make much sense...
What?
Nearly all of the Cybertronian vehicles from other lines and continuities (such as War Within, for example) have doors and seats and looks as though they are meant to be driven by a smaller person...
So who exactly is supposed to pretend to drive them??
I mean it makes sense that Optimus Prime as an Earth Truck has seats and a windhield and doors because he's in DISGUISE and earth vehicles have those things because HUMANS drive them...But why would his cybertronian alt-mode have them?? As far as I know, the only inhabitants of Cybertron are TRANSFORMERS...
It doesn't really make much sense...