I think that bandits in 4 should occasionally spawn in groups going through a town, there would be fewer zombies there because they have been and will be actively killing them. But I think the bandits should also loot things as they go past. This means that players won’t just try to ignore bandits and let them clear a town out.
Bandits won’t take everything, but they will take good gear. If the npcs are low on food they will loot for foot and water. If there is a well they will drink from it, they should occasionally sit down and lean on things.
This would encourage fighting the bandits because they would take loot from towns.
Also if a bandit sees a gun and has run out of ammo, they would run to it and swap to it. This would be interesting with bandits that don’t have guns, as if they saw one they would run to it rather than chase the player.
Bandits should also run if they belive they cannot win a fight. Unarmed bandits won’t chase after players with guns ect.