[throw_a_grenade]

In flight maybe not, but after flight there comes landing, and landing on wheels that have parking brake engaged (because of that interlock) may or may not be safe. Yeah, you can add logic to prevent that, you can add more manual overrides, but eventually there's a point when new feature (even one added "for safety") will cause more problems that it will solve.

[littlestymaar]

That's true that there's a balance between the safety benefit you get from the feature and the overhead it ads for the operators (the key example in nuclear reactor I was talking about has actually caused a issue once leading to the enforcement not an additional procedure around it).

What I meant in my response is that the answer cannot simply be “interlocking in a plane would be too dangerous”, so my original question still stands: why is it the case in airplanes when it looks so fucked up from a train perspective.