Is it a gas or electric water heater?

If it’s electric you can add a tank temp sensor (to outside of tank) and a high current relay to bypass the lower thermostat and turn on the heater on command. When your sensor indicates the tank is at the desired temp you can turn off the bypass.

You might be able to do something similar on a gas water heater, but I don’t know enough about them to say.

Put the shutoff where the water line enters your house.

You won’t be able to stop a leak between your house and the street, but … oh well.

Other option (maybe) is to install a cutoff just AFTER the water company shutoff(on your side).

One of my rentals had the line from the water meter to the house burst (60yo steel pipe) water shooting out of the lawn, so I turned off the water at the meter. When I called the water company they chewed me out because it’s illegal for me to touch their shutoff. However, due to the situation they didn’t press charges. When I replaced the pipe (with PEX) I added my own cutoff just downstream of theirs.

You could replace the relay(if that is the problem), should be fairly simple.

If your switch is connected to the socket and disconnects the ‘hot’ side from the socket, it doesn’t matter if they turn the plug around, there is still no ‘hot’ at the socket.