Different lock types are more or less common in different places.
I don't know where the artist of the comic lives, but here in the UK for example most exterior doors have a keyhole on BOTH sides, and you need to use the key to lock or unlock it from inside, as well as from out.
It does feel like it might be, but I don't know if it actually is.
The UK generally has extremely good fire safety regulations, so if this was getting people killed I feel like it would have been the subject of some scrutiny.
The house I grew up in was this way, and the house I live in now with a new door (<10yo) is still that way.
As a kid I never thought about it, and I don't remember ever being stuck in the house.
The way people normally deal with keys is that everyone who needs a key has one of their own on their keyring, and there is usually also a 'house' key which stays by the door and isn't taken away anywhere.
And none of this is to say "this is a good way" it's just to say "this is the way people are used to here"