It seems the easiest method to stop cable theft is to park on the cable, but that would not stop some one parking next to you and yanking out your cable and plugging in theirs, but one would be likely caught doing that, so either you have turned on your EV charge point, and have a cable attached, or your using the car, so EV charging point is switched off.
At work the first 15 minutes is free, this is so the user can log onto the providers system and register their card etc. We have seen people plugging in and sitting in their cars and unplugging and plugging back in every 15 minutes, at 22 kW this is 5.5 kWh they are getting for free every time they do it, which is likely less than a £1. If their car is single phase only, then 1.8 kWh, I tried to find the cost of a kWh but going round in circles, but the point is would you try to steal electric if likely you will get caught?
Stealing the lead yes, it take minutes, but the electric it takes hours, one of the workers where I work has an electric car, she clearly starts work around 9 am as most of us do, and at 11 am it was still charging, and I noted still a few bars to go on the bar graph on the car, likely midday before she moved it to members car park, so in three hours I would say likely if stealing electric one would be caught, internet says average battery is 40 kWh, so either hers is only single phase, or she has a 66 kWh battery, which seems unlikely.
I did look at it, our trains take around 2 hours return trip Welshpool and back, hers is a really small EV, so not recharging within 2 hours with a 22 kW charge point, means people can't fully recharge their cars while on the train, so one has to question the whole idea of EV's.