I have one in my car because it’s required by law (Belgium). I don’t have one in my house and I don’t know anyone who does.
I do have multiple smoke detectors and carbonmonoxide detectors. The smoke detectors are required by law but there are still people who don’t have them. Last night a family of 6 died in a fire and they apparently didn’t have smoke detectors.
Here in Belgium everyone is a donor unless you register that you don’t want to donate your organs.