Don't be so sure that all, or even most, junior employees know any such thing. I've seen junior employees fired for doing silly things in prod before[1]

[1] Of course whatever more senior bozo granted the junior the rights to blow up the thing(s) they did should have been fired instead. That's not the way things work in the corporate world.

And we only do it once (I didn't kill the db, but I did kick off a process thinking I was in a test environment).

Them knowing that it is bad isn't much of a consolation for the dead production

The magic that happen in someone's mind that leads to their actions matters very little for everyone else. Their actions and the consequences of their actions are what everyone else actually cares about