Nearly Automated Method for Stealing from Dwarven and Human Caravans

Make two trade depots, one that the wagons can reach, and another that only the non-wagon traders can reach. When all the wagons get to the Depot, all the traders will run away, leaving the goods that were in the wagons in a forbidden pile of goods on top of (but not inside) the depot.

I made this discovery quite by accident on version 40.24, on a new fortress where I built an underground trade depot, but had difficulty deciding how to build the wagon entrance. So I just built a temporary above-ground depot for the first season, and discovered this issue. I haven't experimented all that much with this technique, in fact I don't have much interest in stealing from caravans in the first place, as I find it rarely difficult to buy everything I want and then some. But I was curious if this technique is known, it might possibly be an interesting starting point for others to further develop this technique, and this bug is probably worth reporting.