If this isn't the answer, and I'm not asserting it is or isn't. What is, and how do implement it. Or do you suggest if we scrap it all and go back to 1950's like airport security that the few incidents that are inevitable are an acceptable risk? I don't know the answer, but I'd like to have the conversation.
I vote to drop nearly all of it. The cockpit door is reinforced and locked, without the ability to take over the aircraft there is literally less risk than if someone just drove a bomb into an airport.
Which is exactly what the 2007 attack on Glasgow airport was.[1]
All major airports in the UK now have limited access to the front of the terminal building (typically, buses and taxis only). Most now have a drop-off zone in the car park.
[1]: https://en.wikipedia.org/wiki/2007_Glasgow_International_Air...