I’m not an engineer, but I’m not sure I understand why there is any fixed surface area once the mice enter the opening. That is, why isn’t the hole in the surf

I’m not an engineer, but I’m not sure I understand why there is any fixed surface area once the mice enter the opening. That is, why isn’t the hole in the surface of the trap a rectangle (the shape of the cover) instead of a hexagon (the shape of the paddle)? That one mouse (out of 101 mice) that got away was only able to do so since there was a non-spinning surface for it to grab on to. Unless I’m missing something, it seems like a simple solution would be to just make the opening a rectangle, so that once they entered, the only surface they could walk on was the spinning paddle. I’m not sure why the inverter — or the production engineers — didn’t think of that. But again, maybe I’m oversimplifying it.