That’s news to me that key-in is enough to activate enough electrical circuits that it can drain a battery. I wonder if that info is in the owners manual for these vehicles. I would want to know that about a car I own.
My worst key-in experience was in 1996. The switch on my 1983 Corolla wagon was very tricky and it worked better if I just left the key in. One Saturday I drained the coolant. That night my neighbor called - he’d heard on his police scanner that someone driving a car like mine was being chased. I went and looked and my car was gone! The car quit, the kid ran, the police got him and my car was towed to the station. When I got it back the head gasket was shot and the heater control valve had melted. I replaced the gasket and valve and the car ran OK despite the severe overheating. I submitted an accounting of my expenses to the court.
Fast forward to fall of 2018, 22 years later. I got a check for $403.24, crime victim compensation, thanks to the WI corrections and court systems.