Great observations.
I think it’s nice to see some differentiation to eliminate the endless possibilities of the buttons on current microwaves, but in the end fails. I’m sure if you point it back to whomever created the designs it wasn’t fully understood (which I believe you need to completely understand something in order to simplify it) and/or had no user validation or they didn’t listen to it…
Something so minimal on my current lower-end microwave (being a college student!) is that the controls are all the same color, and that Start and Stop/Clear are on opposite sides on the bottom of the keypad. It’s about a 50/50 chance that I actually hit start on the first try. A simple color addition of Green on the Start and Red on the Stop/Clear would remove this error.