No those mental rules EV old timers created for themselves can go away. Do not touch other people cars!
There not touching the other peoples car are they though - There touching a public charger, that OP could be in tesco for another hour occupying while there having to wait to get some charge to continue there trip.
I know many rapids will completely stop charging at 80% to try and stop this issue -which is likely what occurred here - a rule created not by the people, but the chargers themselves - because its sensible.. for now.
People in EV communities for some reason created themselves crazy honour system they try to hold others accountable to
The reason is quite simple really. Unless you own a tesla, there is a very small amount of rapid chargers for an ever increasing amount of EV owners. Rapids are needed 24/7 - weather its in a tesco, or a proper EV charging station. You never know what issue might have occurred that means someone has to make an unexpected stop at a rapid, sudden hospital visits for instance. Point is, if you are done with the rapid for the journey that you need to make, you really should vacate the space - Until they become widespread enough that it is not an issue.
You don't get to decide how much charge other drivers need.
To continue on this part - After 80%, charge rate on rapids plumet. making matters worse, rapid charging shows up the internal residence differences of the different cells, so rapid charging to 100% can throw the pack on a wobbly - this is why some cars point blank refuse to charge to 100%
In short, I wish I could agree with you, and hopefully I soon can - You should not unplug someone else's car, and i frankly don't like the thought of the car throwing a fit because its been unplugged while locked.. But for now, with the extremely limited amount of rapids, i can tolerate it if the car has got to or exceeded 80%, or stopped charging - Judging by the charging connector being unlocked, i'm guessing the latter happened in OPs case.