This is a common question that gets asked by consumers. So, why does shapewear have a hole?
Actually, the hole in shapewear is called a "gusset." A gusset is a piece of cloth that allows you to use the bathroom without removing your shaper or underwear completely. You can go out undies-free and just open up the gusset before using the toilet.
Shapewear is supposed to fit snugly against the body. It should not be loose, bunchy, or have excess space between the body and the garment. The shapewear should also not be too tight so it causes any discomfort or pain to the wearer.
It can be difficult to roll down the high waisted version of the garment, especially when worn together with a low waist skirt or dress. If nature calls, you need some level of dexterity and talent as a contortionist in order to successfully accomplish this feat.
The hole is for accommodating bodily functions like peeing and pooping without having to remove your entire outfit for those moments of relief.