A square object like a box would not sit properly in the rounded base. During transport the box could slide right off of the base because it is not sitting securely. Another type of specialty truck is HVAC, which is suited for the heating and cooling industry. Its shape is tailored to fit heater, ventilators and air conditioners.
Unlike the drum truck, the shape of the HVAC truck means that it is able to carry more than just heating and cooling equipment. Distributors and manufacturers also use the HVAC truck because it can handle large and bulky boxes.

The design of a truck is so versatile that people from all industries take a crack at designing their own model. There are trucks for vending machines, appliances, pallets, drums, bags and boxes. In some designs the focus is not on the items being carried, but on the situation in which they are being used.
These trucks designed for situations result in some odd combinations. Combination trucks take the basic idea of a hand truck and build on it. What if you are using a truck and you come across stairs? Then you get a stair climbing truck. What if you want a truck and a dolly, but you do not have room for both?
Then there is the convertible trucks that can be one or the other. Out of this burst of creativity came some strange combinations.

For instance, there is an all-in-one truck, dolly and step ladder combination. The creator of the device fails to mention any situation in which it may be useful to have all three at the same time. If you use the step ladder to take something heavy off of a shelf and then convert the step ladder to a hand truck, that is quite a lot of trouble and effort.
It is dangerous to lift heavy object from high places as well. The device perhaps makes sense to people using step ladders and trucks frequently, but there is an awful lot of deconstruction and reconstruction involved in using that product.