Adding back open tailgate has become popular. In the past, wagon folds in two direction were more convenient and portable compared to quad-fold folding wagons, but had lower volume and load capacity. Now adding a rear opening gear adds invisible volume. When you are camping or fishing, there must be some long objects, such as umbrellas, tents, fishing rods, which are not heavy but long enough to fit in an ordinary cart, and this is where the advantage of having a rear opening gear comes into view.
link:https://www.toursporting.com/beach-wagon/assorted-colors-utility-outdoor-folding-wagon.html