Legally I don’t know, but morally I’d say no. If I was a restaurant owner who had paid for a charger to entice customers with EV’s, I’d be pretty hacked off if someone who wasn’t a customer pulled up and plugged in and used my electricity. Bit of a cheek really. Personally, I wouldn’t touch an EV without the ability to charge at home (which thankfully we have) as we don’t go to supermarkets etc and a refuel at a petrol station that takes less than 5 mins every 3 weeks or so is enough for me and I just couldn’t be putting up with even 20 minute stops for an 80% charge, but if I was in that situation I guess a supermarket is the best option as it’s not so obvious that you aren’t a customer and at least it’s somewhere to kill the time whilst the thing charges!