Tunnel access points don't care if you're coming or going, unless an opening can only be traversed in one direction.
(Assuming the ladder is placed by the investigators)
It has an electric winch, so this basket could both deposit into or extract from the tunnel. If that tray is able to lower a child (as is being implied), a lot of fent or other drugs could also be lifted on that thing quite easily.
This is not necessarily a one-way entrance, unless you are trying to paint an exclusive narrative… as is happening in that post.