Because the GPS time scale is fixed. UTC drifts by leap seconds, GPS ignores them. I'm not sure what the point of the stackoverflow link is, because it certainl

Because the GPS time scale is fixed. UTC drifts by leap seconds, GPS ignores them. I'm not sure what the point of the stackoverflow link is, because it certainly says as much itself. Yes, I understand that additional leap seconds are added as time goes on, which makes the difference between GPS and UTC larger as the years go by. But this doesn't mean that the GPS time scale isn't fixed.