there's actually plenty of ways to escape. at low levels, fog and invisibility, grease and web. once you have access to teleportation, escaping is trivial. If the party doesn't have any of those, not even a scroll saved for an emergency, then it's really their fault. Can't say "but the system does not support escaping", because it does.

Even in the worst scenario, where there is no escape magic and the monster is faster than anyone, you can have everyone run in a different direction; instead of a tpk, one single character will die. And then you can resurrect him for 5000 gp, which is available even to low level parties.