I don't think it's possible to know when the first car is finished. It's up to them when they finish.
That's interesting. I thought (and I'm not sure why) the car released - as in unlocked - the cable once it's charged to whatever level (e.g. 80%) you set so the next man can unplug you and plug himself in, assuming you're not about.
I don't have the answer to that for definite. All EV's, afaik, have an emergency release cable to release the charger if it gets stuck. So maybe getting stuck is/was common enough to warrant the emergency release cable?
The MG5 does release the charger when I stop charging but you can't rip it out when it is charging. Once the external charger 'froze' at the initial 'handshake' and wouldn't release the cable for maybe 5 minutes. Only happened to me once though.
In the MG5, you cannot program an end-point to stop charging at an
external rapid charger because... (I'm sure it's more complicated that this)... the DC goes straight into the battery and the Battery Management Software (BMS) only has a little bit of control of it.
I also understand that, industry-wide, BMS software is still in the infancy stage and there isn't enough agreed communication protocols when it comes to charging. So the charging stations take the lowest common denominator - charge on & charge off & a few other things. Some home chargers can stop at a certain percentage but I believe that's the charger doing it and not the car's BMS.
The technology is evolving rapidly so I'd bet there are new EV's out there that are clever enough to do all the above.