Using the UNLOCK button:
You have to press the UNLOCK button twice to unlock the hatch. But then all the doors are unlocked and you will have to press the LOCK button to lock all the doors (and the hatch)
Using the HATCH button:
You press and hold the HATCH button to unlock just the hatch. The doors stay locked. Then, when you close the hatch, it automatically locks the hatch.
So you either press the UNLOCK button twice and then have to press LOCK or just press and hold the HATCH button one time.
Here's another reason it doesn't "pop" the hatch and why I prefer it just unlocks.
Hatch popps: if you accidentally pressed the button, or pressed the button, got distracted and forgot to open the hatch, then the hatch would be unlocked if you walked away. Your hatch is now open for a thief to access your car.
Hatch unlocks: if you accidentally pressed the button, or pressed the button, got distracted and forgot to open the hatch, then the hatch would relock after a few seconds just like the doors do if you unlock then but don't open them. Your hatch is now secure and a thief could not access your car.