The most people are 'told' how to live, the less capable we become of making our own decisions, meaning we need to be told common sense things, which becomes a vicious cycle.
It's also (as horrible as this sounds) an absolute fear of death (and discomfort). When it's really hot (or really cold), human beings can die as a result. That's not a nice thing, and I certainly don't mean we should be fatalistic about it (and I certainly don't want my or anyone else's grandparents, etc, to suffer during the heat), but it's what being living beings can mean sometimes. Which isn't to say don't be sensible (and there's nothing wrong with being reminded about hot weather sensibleness, given we see so little of it here!), just that it's not an excuse for the government (or the leaders of the o̶b̶l̶i̶g̶a̶t̶o̶r̶y̶ ̶s̶t̶a̶t̶e̶ ̶r̶e̶l̶i̶g̶i̶o̶n̶ the health service to fly into panic mode about either.
