While it may not be the last word in security, I've been using a weatherproof cover over my electrical outlet at my parking spot. I can't find my exact unit right now, which i bought at Home Depot… but it looks just like this:
https://www.lowes.com/pd/Hubbell-Ta...ic-Weatherproof-Electrical-Box-Cover/50372928
It protects the plug/receptacle from the elements, but also has a small tab at the bottom of the hinged door cover through which a small padlock can be attached, which I've done. This prevents the cover from being opened, and the plug from being disconnected. (I use a combination lock, so if there's ever an emergency where someone else needs to disconnect it they can do so by calling me and I can provide the code to them.)
Strictly speaking it wouldn't stop anyone from cutting the power cable, smashing the plastic cover, or physically pulling the entire outlet assembly from it's connection. But it does deter and/or prevent someone from just unplugging it and walking away with your EVSE, and they'd have to make some noise to do so - which is probably enough of a deterrent for relatively safe neighbourhoods.
The only real downside I see, is that it's a bit more of a hassle to unplug the EVSE if I want to bring it with me somewhere. But I still find it's worth it for my peace of mind.