Basically, the rocket is designed to withstand the extreme conditions of a launch, and the satellite is typically safest inside the rocket during this process. Adding an ejection system, which would allow the satellite to separate from the rocket in the event of an emergency, would increase the weight and complexity of the launch vehicle. This would also increase the cost of the launch and add additional risk to the process, as the timing and conditions for an ejection would need to be carefully planned and coordinated. Ultimately, the decision to include an ejection system on a rocket is a trade-off between these factors, and in many cases, it may not be worth the added expense and risk for a satellite launch.