Fred,
I use a Master Tow 80 with surge brakes. I believe the reason for the locked steering column on the Master Tow may have to do with the rotating carrier pan. The rotating pan allows for better tracking of the car around corners and eliminates some of the effect of the coaches tail swing.
The Master Tow requires the wheel locked and trans in park when towing.
I primarily tow our 2008 Ford Fusion but have also towed the Ford Flex.
The reasons for me choosing the Master Tow were
The rotating pan
Fenders over the tires
LED Lights on the Dolly (I do use magnetic lights on the car trunk as well by using an adapter that allows plugging in two sets of trailer lights)
Normal size tires and wheels.
I did install a crank down trailer jack (purchased from Outdoor world) after this pic was taken.
Here is the dolly connected to my prior coach with the Fusion loaded. We were heading to Fort Wilderness this past January.