Someone just took an old design and updated it to newer tractor with a wide front end, those setups were pretty common years back, anyone who moved a tractor used them, and pulled it behind a pickup. Its been a few years since I've seen one used, but I've seen dozens of dolleys on sales in the past few years, they also made them for widrower's so someone could pull a hydrostatic drive machine miles down the road to the next job, also behind a standard pickup. In my state its still perfectly legal to tow those behind anything, just like in the pictures, not even tied down.