That they went to print with the braking system explanation completely backward is a travesty of Journalism.
The reason for the difference between trucks and trains is a result of the amount of braking force required, and limits in practicality.
The size of the springs, the force they exert, and the breaking force required for trucks makes spring actuated air released brakes unworkable.
The size and force of the springs required for a train would make it impossible to assemble the braking system. And certain breaking systems just would not physically work.
An air, or fluid actuated system is the only viable ways to do it.
Since you want the system to apply on loss of air pressure (the line is broken), then you want a reservoir on each unit that is used to power the brakes. And a control line that will engage the brakes if the control pressure drops.
The onboard reservoir will supply breaking force long enough for the operator to correct the line problem, or apply hand breaks.
If the control line is disconnected, and the car is just left there, then the pressure will bleed down and the car will start rolling. It isn’t a mater of if, but just how long until it happens.
Sadly, this doesn't even make the top 20 for me.