Having a Sanparks Wildcard does NOT give you access to the Kruger National Park

We are a family of 4 and have a Wildcard through Sanparks. Even though our card is valid, in order to visit the Kruger National Park for a day, you have to pre-book. If you don't, you will not be lucky enough to get into the Park. Why has Government made the Park only accessible to the rich? Kruger National Park is supposed to be enjoyed by all South Africans, yet we cannot access it unless we spend an extra amount over and above the Wildcard. This is really terrible.