Most SUV's are Rear Wheel Drive.. Dolly's are for Front Wheel Drive cars.
Now a Mini-van/crossover may be Front wheel drive
But most SUV's are RWD.
Although it is possible to tow a RWD vehicle backwards on a dolly but you have to tie the steering wheel (do not rely on the lock).
Frankly, i think they are a big hassel which is why I modified my car so it can be flat towed.. This cost about 1500 dollars (Few more or less depending on the tow) and it can be done to most all two wheel (Front or Rear) drive vehicles.
Some of the mods have other advantages too.