Older cars had electronics that drew that amount, mostly engine controls and entertainment systems.
Modern cars with CAN (controller area network) turn the transceiver on and off. When awake LED's in each device draw about 20 mA. When all are asleep they each draw micro amps while listening for a signal. That is why old and new cars draw about the same amount when switched off.
Some modules develop a problem that does not allow sleep, and just like noisy neighbors, they keep everyone else "awake."
You can disconnect different modules to find out who is the bad actor. Problem is they are located all over the car. Some require considerable time to expose using this technique, whereas a dealer can use his online tools to point to the bad boy.