My guess is that it's borne from a horse and carriage, but that was 100 years ago. Have designs really not evolved because of habit? What about, say, a joystick for steering? Or a center-placed driver, instead of off to one side?
Designs: It seems these things change with generations like clothing. You know an 80s car when you see it, for instance.
Related, it seems over time cars are getting bigger and bigger (eg 1995 vs 2019), and more "marshmallowy" and rounded and less distinct from one another. I assume this is due to safety standards limiting creativity. How much is simply design choice? How did tail lights go from this to this to this?
I can say that the control layout was wildly non-standard until the 1916 Cadillacs introduced the scheme we know today with steering wheel, clutch to the left, brake in the middle and accelerator to the right. Before that (and to certain extent after as everyone figured out Cadillac had gotten it right) things were a confusing mess, with controls laid out across pedals and levers and Johnson bars (lever with a locking "spoon" on the handle) in whatever fashion the designer thought was right. Moreover there were controls that have no relation to the ones we know of today, or that operated in unintuitive ways or even changed function based on what state another component was in. For instance, the Ford Model T drives more like a tractor with a hydrostatic transmission than an automobile; the leftmost pedal is pressed down to go (it is very heavy, like an oil-truck's clutch) in low gear, and released to go in high gear, like the accelerator on certain Soviet tanks (whose designers were worried about soldiers having to hold down the pedal on long road marches). There are two brakes, one is a lever and the other is a pedal, neither directly correspond to the service brake and parking brake on a modern car. On the steering column are two levers, these are the spark advance, which has for many, many decades been automatically controlled, and the throttle proper. The central pedal was for engaging reverse when the car was in neutral. So at least in high gear you can go along without positive input on any control. Before modern cruise control but after the controls settled on what we know now, there was a convention of providing a dash throttle for this purpose and also for allowing the car to warm up if it were cold out. You may still meet them on trucks where they are used for the power take-off function (for a winch, generator, compressor, hydraulic pump, etc.) and for having the truck amble along slowly as you walk beside it throwing things into it or suchlike.
I don't know how the style evolved generally nor what drives this change. The hideous, bulbous "bio" look of everything today, fashioned as if it were extruded from the baleful orifice of some black beast from beyond the stars, is after the Ford Taurus, which replaced the LTD, which looked like a car. This change was a very pronounced one.
