Why are there so many steps to starting an engine on a plane? Why not a turn-key start?

Here is a thread from 2014 on the topic.
[A Question for the Pilots Here.]

In there we hear from light plane pilots, airline types like me, and a wide variety of perspectives. I also give the ultra-abbreviated version of how much of the airliner-scale pre-start process can be skipped and still actually get the fires lit and the airplane airborne.


Directly back at this thread's OP: The vid you chose shows a machine about as complicated as a locomotive or a 60' yacht.

For a simple Cessna-like product with just one ICE that’s more comparable to a car, there a 3 steps to start the plane: electricity on, mixture knob/lever forward, turn key. Vroom!

Contrast that with a manual transmission car: ensure transmission in neutral, depress brake and/or clutch, turn key. Vroom!

An auto tran is simpler: depress brake, turn key. Vroom!