Another point is, I think the general public had MUCH more common sense in the old days than today's dumbed-down society. We got along just fine without seatbelts, helmets, & government sticking their nose in every aspect of our lives. Had we not, we wouldn't be alive to be on this here forum!
Lots of people are lazy, and lots of people these days have no qualms whatsoever putting the almighty dollar above human life. They'd rather save a few bucks than do NEEDED maintenance to heating devices. The other part of THAT is, the costs of maintaining a building have gone through the roof, and property taxes/ government regs. just continue to rise - that doesn't help things either.
I didn't have a CO detector for years, but, I'm aware of my equipment - it always gets checked. This house has enough air leaks that CO poisoning would be very difficult here anyway. I'd be awake to the problem before it got to the point of no return. I know this because it's happened before - with and without the detector.