So, it really depends on what game I'm playing. But for now I'll stick to talking about my D&D 5e games.

I'm a very by the books DM. I don't cheat rolls. I don't ignore rules. And for things not covered explicitly by the rules I reach of an existing tool within the game rather than inventing my own. I also don't care much for "balance". I lay down my adventures the way I think they should be and if the players wander into some part of it they can't handle, it's on them to realize that and take action.

That means death is on the line in fights. Now, with the death save mechanic and cantrips like Spare Dying, a true TPK is nigh impossible and individual deaths are rare but they do happen. Here's all the things that have happened about PC deaths in my game.

Temples will raise the dead for a 2500gp "donation."
One player had the party give the corpse of his dead character to some elves for safe keeping while he made a new character to go on quest to raise the dead character.
One player has just let it lie and makes a new character each time, no problem.
A few high level casters have raised dead/greater restored a petrified character in exchange for favors.
One group I gave a magic book that will raise the dead of anyone whose name they write in it. However, this binds that person to a demon who will need them to "balance" the books later. This has the creepy visual effect that whenever the demon manifests their characters are literally attached to it with chains.

So yeah, I don't cheat death and no one is saved by anyone's "benevolence". But if players really don't want to lose their characters there are ways around it but the cost is high in money, blood or labor.