They get used a lot as trade vehicles to carry around tools and materials. Its much more likely to see a tradesman/contractor here driving around in a ute than a van, which is more common in Europe. Ute is short for utility, and is the exactly the same in principle as an American “pickup”. As to why we use them instead of vans, besides the long-standing cultural image that “it’s Australian”, I have no idea. It could be because some of them have huge engines/go-fast-bits while still being able to cart things around.
The panelvan, despite its notoriety, was presumably targeted at being able to camp in the back, rather than setting up a tent, and still being able to fit in a surfboard etc.