Why don’t sandwich toasters have an on/off switch?

The absolute majority of electrical appliances have an On/Off switch. However, the absolute majority of sandwich toasters do not - you just plug them into the socket and unplug them when you're done. At least, that's the case for all household sandwich toasters I've ever seen. I'm referring to this device, not the vertical toaster (where the lever doubles as a switch):

It looks like some models do have a switch, but apparently these are just the larger/industrial types, not the common variety.

Why is that?