The red line allows the elite "security forces" to sit on their ass in one spot instead of actually securing the flight line. That way, the red line only is a hindrance to people who give a shit about the red line. Everyone is special in the Air Force, so pilots walk well out of their way to avoid stepping over a line painted on the ground.
You are implying that AF pilots walk to their jets when they "step". That's what the crew vans are for. Those people don't walk anywhere.