Even cheap toasters (I take toaster apart for fun) have true electronics these days because it's usually cheaper to implement things like timers electronically and if the toaster has a display it certainly has some electronics. But I suspect that the absolute simplest toasters are purely mechanical and electrical.
I was curious so I did some searching -- this is the cheapest toaster that I'm aware of in the US, and it surprisingly does have a custom IC that handles the timing: https://www.youtube.com/watch?v=zLFG068HtgM