I understand your question. It may seem counterintuitive, but the horizontal speed of the package just before it hits the ground is not 30 m/s, even though it falls off a truck moving at that speed. Let me explain why.
When the package falls off the truck, it is no longer in contact with it and is no longer subject to its forward motion. Instead, the package follows a projectile motion path influenced only by the force of gravity acting vertically downward.
The horizontal motion of the package, perpendicular to the force of gravity, remains unaffected. This means that the package will continue moving horizontally with the same speed it had when it fell off the truck until it hits the ground.
Therefore, the horizontal speed of the package just before it hits the ground is still 30 m/s, assuming no external forces or influences on its motion horizontal to the ground.
I hope this explanation helps in understanding the concept. Let me know if you have any further questions!