Yes, the math is the easy part, doing is the hard part. The difference between understanding and doing is large and denial, shock, rumination, and rationalization all fuel inaction and there is often a moment in which it becomes too late.

People on death marches, in concentration camps, or other similar scenarios have the same math, and yet they get gassed or forced to dig their own graves after which they are shot and buried in them.

So yes, rationally that all makes sense and we should celebrate anyone putting themselves at risk to fight for the benefit of a larger group, but reality is different, especially if the hijackers can guarantee at least one death.

To say a hijack could never happen again is wrong. The doors are a much more reasonable explanation than the courage of men.

History also gets forgotten, such as the history of secret police or mass deportation efforts as is quite clear in this thread.

Airport security has rendered passengers equal. There is no imbalance of power that exists in all the examples that you provided.

Assuming something is true doesn't make it true. Colluding airport employees as well as rural airports seem like clear vulnerabilities. When thinking about security problems you don't just assume your security measure always succeed and assuming that all passengers are "equal" seems like a poor assumption, especially for an exceptional case by highly motivated people, potentially with state backing.

https://en.wikipedia.org/wiki/Air_West_Flight_612

Here is an example where a man got a gun on a plane in 2007, which directly disproves the 'equality' if passengers.