Commercial passenger airliners are similar to public transits. The operator determines the route, and passengers take them if they fulfill their needs. On the other hand, a private flight is similar to a taxi. The passenger determines the origin and destination of the flight.
There is currently no airliner providing a route over Antarctica, and flat-Earthers use it to “prove” that it is impossible to fly over Antarctica. In reality, the airliners simply decide not to provide such routes due to commercial or other reasons. Not because it is impossible to fly over Antarctica. We can take private flights if we really want to fly over to Antarctica, just like we take taxis to go to a location not serviced by public transit.