Don't be misled by the photo.They actually DO exist!!
The visitor to Japan will never find them for the following reason; (The quote beow doesn't apply to the photo above but that machine will certainly be included. *Gachapon is a different type of vending machine where the goods appear in a plastic ball but again, the same applies)
Above the price (Yen500) are the words “スーパーUSED加工” (super used kakou). Kakou, in this case, means that the panties were manufactured to appear used – kind of like the Abercrombie jeans that are sold with holes and frayed edges straight from the factory. The addition of those two kanji characters makes it instantly apparent to a native speaker that the panties are not, in fact, used. Perhaps an enterprising *gachapon machine salesperson realized that they could trick non-Japanese into believing the urban legend by slapping a single English word on the sign
A more balanced account appears here;
Panty vending machines