This assumes a car with a working cooling system. How many people have old cars with bad head gaskets or a radiator leak and “just fill it with water” and not fix the problem, only to find that pure water isn’t enough, as modern cars will walk up and down from 185-235F, which will blow steam before the fans kick on. They never noticed because they only drove a few miles a day, not long or hard enough to find out there is a real problem and not a nuisance.