> The accused are punished, sometimes even executed, without anything resembling due process.

I also don't like this but I wonder, if this is because the choice is between a) full punishment with less certainty of guilt now b) lenient or no punishment with high certainty of built later.

The ideal would be to hold those people until they can be tried and punished in an orderly fashion. And in principle all you need for this is enough food to keep them alive, though in such situations, even that might be a luxury.