|Photo credit: Herbert Wong (photo source here)|
The PVC bag like the one shown above has various uses. The intended purpose for the bags in this pic is for garbage collection by hikers. A strong point in using the PVC bag is its holding strength. Very few comes close to beating it. They can take on a heavy loads e.g. 25 kg, and higher. This is especially useful for the hiking community when garbage are collected; accidental dragging can happen when hiking over long distances and this is where it shows it power -- no tearing! This is totally unlike standard garbage bags from grocery stores; one has to wrap a second layer over it.
The additional weight compared to standard, or thicker garbage bag is really negligible. However, as for the price, it is more costly. Given the capacity, it would be a waste if the bag is not filled.
Another use for it, which is what I want to mention here, is for specific hiking purpose i.e. as a sitting mat or ground sheet. View the photos below for explanation.