Greasing new wheel bearings and hub.

Could never understand why the space between the inner & outer brgs was packed with grease...
Maybe the assembly line workers had stocks in a grease company....
Centrifugal force throws the grease out of the brg, no matter how much you initially pack into the brg. It is amazing how many miles the brgs last with no fresh grease.
Quiz question: if roller wheel brgs last for years carrying the weight of the car, why do needle rollers in roller lifters need a pressurised oil feed?