Then it immediately occurred to me that a toaster has some binary enumeration of the blackness level of the toast, like from 0 to 15, and this corresponds to a non-linear way to the actual darkness: i.e. yep, you have to know something about gamma.
In the 3d printing world, we have a filament of PLA (corn based plastic) with wood dust mixed in the plastic, of around 20%. This gives a filament that feels, machines, and colors like wood.
And if you extrude at varying temps, you can give the part lighter or darker colors (darkness dependant on higher temp).
I can almost guarantee that there's no gamma correction, let alone darkness calculation, being done for filaments like that. And it would follow an inverse power distribution - the more heat, the higher the power and the lower the final energy result (burnt = lower potential energy in wood).
So yeah, even if you don't do graphics, it still applies. Damn...
Only if it's a fancy commercial toaster with optical feedback then gamma correction could matter.