Doesn't smoke also wake people? One of my roommates once tried to burn my door down. The yelling and screaming prior to that didn't wake me up (I thought it was just part of a dream, I guess it was a REM sleep cycle), but the coughing from the smoke eventually got me out of my slumber. I'm pretty sure the body has a built-in smoke detector.

I think you seriously underestimate the threat of a real fire - a mistake which a lot of people (rather sadly) make. People die in house fires because the do not wake up in time to get out - the place goes up pretty quickly, and smoke (+ poisonous gases) incapacitate and suffocate people before they even have a chance.

Many resources in this area, but as a starting point: https://www.ready.gov/home-fires