By rare, I meant the scenario where the starting bandit lair is close enough to the road when we generate a new campaign, or close enough to get help from the caravans — at least something I haven’t seen yet (or because I haven’t really tried to do it) in 20+ games started (I probably have 3 campaigns that I played for long, but now I started to do “ironman” campaigns and the start is really rough, especially at Hard, so I’ve wiped many times)
When you get that nice placement scenario though, then I can see how you could do it every time a caravan passed by, but then the lair gets destroyed once and that’s it, unless another one spawns close to the road. The rest of the lairs are usually far enough from the road that caravans are out of range, at least from my experience so far.
You bring up a good point though, like why would caravans go out of their way to help us destroy a lair, or in general participate in offensive battles, especially since they bring with them the veritable Donkey? I would recommend lairs in general start far enough from the city/roads, as it would also make more sense lore-wise; and in that case caravans will never be in range to help against lairs.