Even if oven fires aren't likely, it's definitely weird that my microwave will beep every minute until you open the door just in case you forget you need to eat to live, and my oven will happily run for hours (days?) and doesn't seem to remind you about how you might be accidentally incinerating something, it seems like a beep every hour (with a button to mute it) wouldn't be unappreciated.

Although I guess if it's not a safety thing, the cost of the extra design might be more than I'd expect to save on my electric bill from the once a year or less I leave it on overnight by mistake.

Exactly, my microwave plays this cute little song for about 3 seconds that stopped being cute after the second time hearing it. But if you don't open the door within ~30 seconds or so, it plays its song again. It does this for a long while before giving up. Customer support, when asked if there was a way to disable it that was missed, said it's a "safety feature" and therefore cannot be disabled.

>it could burn my house down if left unattended

Really? I have a hard time imagining how heating elements in a steel box is going to burn your house down.

Imagine an in-wall oven that requires the use of an active blower to keep the surrounding area from getting too hot.

I've also had an electric oven where the element was damaged and started melting/deforming. Not sure how far this would have gone if left alone.

> In this condition, it could burn my house down

You’re pre-heating your oven, so it’s empty. There are no realistic circumstances where an empty oven could burn your house down simply by being on at a preset temperature.

> You’re pre-heating your oven, so it’s empty.

This is a big assumption. A lot of people, myself included, store pots and pans in the oven when it's not in use. I frequently forget to remove them before preheating.

In my case the pan that I keep in there is made of cast iron, so there really isn't anything that can go wrong. But I would bet good money that there are people out there who keep wooden handled pots and pans in the oven. Is it a bad idea? Absolutely. But it's a realistic scenario.