The vehicles I have towed have never had that problem.
The 2006 PT Cruiser is towed on a steerable dolly, so the ignition does not have to be on to unlock the steering.
The 2006 Jeep I used to have had an "OFF, not locked" position in the ignition switch, so the electrical system was not energized when being towed.
The 2001 Dodge 4X4 also has the "OFF, not locked" switch position.
If, by some strange quirk of fate, I ever happen to get a vehicle that has to have the switch ON while being towed, I will either disconnect the battery or install a charge line from the towing vehicle to the towed so that the battery in the towed does not go dead.