I agree, would this mean the AI needs to be edited though since there's no collision for visitors witj the construction items anything blocking the path the visitors will just pass through. With terrain however I feel that there would be collision and that the AI might start to bug out if they decide a path isn't wide enough for them to fit through even though it might look like it is.
I think it's currently designed this way to make sure the AI works well with the paths and tunnels.
