Well if you don't need one, you don't need one! Mine travel in a cage in the car. not only does it stop them eating the shopping, its also crash resistant so a safety thing and gives me total control when getting them out of the car and you also can't shut the car door on paws or tails. When they were pups I had a cage indoors and they went in it if i needed to do something where I couldn't give them my full attention (vacuum, shower, go to the loo and so on) also at human mealtimes so we could eat in peace. As soon as that wasn't necessary we stopped doing it. Some dogs like to sleep in the cage like a cave but ours never did so we took it down and put it away. They can be useful, not essential, except I would never travel a dog in anything else.