Why American built 5th wheels?

At this stage there are no fifth wheels mass produced in Australia. Fifth wheels have been mass produced in the US for decades. They have had decades of design improvements and because of the massive numbers produced are relatively inexpensive. Fifth wheels in the US are about as common as conventional caravans. In other words you see them everywhere. In many US States they greatly out number caravans and motorhomes combined. The great advantage of the Ultima range is that it has been designed by Australians, purpose built for Australia with the mass production techniques and decades of experience only found in the US.