Agreed, it's inconsiderate, but it does occur frequently. Some terminals allow stiff extra charges to be incurred after a certain amount of time parked in the space. That tends to get the cars rotating.
It says "never unplug a car without permission." If someone is fully charged, what's the harm in unplugging? I don't agree with that one at all.
If the driver of the plugged-in car is not one of those considerate enough to move their car after it is fully charged, the driver should at least be considerate enough to display a sign saying it's OK to unplug after the car is fully charged.
Having never used a public charger... How does somebody (other than the owner) know that the vehicle is fully charged? Is there always a display / indicator on the charging station that somehow identifies the state of vehicle charge?
Public EVSEs don't all operate the same way. My sign would say that my Clarity is still charging while the green charge-indicator LED in the car's charging port remains illuminated.
Today, I was amazed at a most egregious example of bad EV-charging etiquette. I had just finished charging my MINI Cooper SE at a DC Fast Charge kiosk and was leaving the parking lot as a Porsche Taycan pulled in. I paused to see if the Taycan was going to charge. There were two charging stations, each with its own parking slot, as is custom. The Taycan ignored the parking lines and parked at 90-degrees, occupying both parking slots and blocking both charging stations. I was tempted to return to the charging stations just to see what the Taycan driver would do when another EV showed up, but decided to vent on this thread instead. The charging stations were marked "125 kW Shared," so I can imagine that the driver didn't want to share any of those kWs with another EV and blocking both spaces and walking away would ensure the fastest charging speed. I should have taken a photo to post on Plugshare.
I wouldn’t ever unplug an actively charging vehicle… but I have pulled a handle on a car that had stopped before. This particular EVSE at an airport had a “charging” light on it, so I could tell it was not running. I even replugged the car and it immediately shut off again, so it was clearly full. That Karma was still there an hour later when I left… makes me wonder if they had any clue.