That's not really clueless. I also lived near an overpass with ramps (where you can get on/off the upper street by a ramp, which is, naturally, unidirectional)

That's not really clueless. I also lived near an overpass with ramps (where you can get on/off the upper street by a ramp, which is, naturally, unidirectional) and since the upper street was not divided it was possible to drive on a ramp in a wrong way. And I have seen couple cars doing just that. From my understanding, quite a few drivers do not really know traffic rules beyond "red means stop" and just follow other cars. If there are no other cars to follow they quickly get confused by any unusual road structure.