Train artillery requires a base. Artillery agros biters, so they navigate to the location of the train. If the train is still there, it gets destroyed. If the train isn't there, the tracks get destroyed. And in any case, the train isn't automated: it doesn't drive out to where they are and kill them. The train artillery just makes more sense than stationary artillery: it has the same range, and it is the most effective way to transport artillery shells. Think about that for a minute: the most effective way to transport artillery shells to stationary artillery is to send it in a train artillery wagon. Why the fuck would you build stationary artillery! LOL!

Spidertrons are also not automated. They don't patrol. They don't run away when they are out of ammo, come back and reload.

Love the MIRV: like the too-short-range nukes on the spidertron, they are a great way to bomb yourself back to the stone-age. The video nicely shows how it's first missile on automatic mode blows up his own base. Brilliant.