That's because you're uneducated, ignorant, and haven't even bothered to find out. Not to mention that you're an abject moron, to boot.

If you wish, please ask me, and I'll explain it, beginning with the apparent movement of electrons in a wire. You'll need some patience, of course, since it will take me a very long time to explain how bread becomes toast to someone as ignorant as you are. But, I'll be happy to do that.

To various foods that are transformed scientifically by the process. In this case, the same heat that toasts the bread (sometimes up to FOUR slices!) heats a bimetal switch that releases a demonic device known as a "spring" which causes the slices to pop up (inexplicably, according to the conservatively under-informed.)

Voila! Your toast, sir.
Edit to add: Also,
Voila! You're toast, sir.

you can't explain that.