[rob74]

If you take a look at the airport diagram (https://www.faa.gov/air_traffic/publications/atpubs/aip_html...), it just takes one wrong turn to end up on taxiway J instead of taxiway K. And, also from that diagram, once the American plane took the wrong turn, the controller had very little time to see that and stop it before it crossed the runway.

But still, if pilots internalize via training that "if you are about to cross a line of red lights, you are entering an active runway without having permission to do so, so don't do it", that should be one more layer of safety to prevent situations like this. Of course, none of these layers are 100% foolproof, but taken together...