Cos development faster than people moving there to stay.
On the side note.
This area used to be swamp land, palm oil plantation with plenty of chicken farms that breeds berbillions trillion flies!
Initial houses built encountered settlement, making plenty of cracks, door & windows gone out of shape. Many houses have to be rebuild with better foundations.

But the worse was the flies!
Insects screen do not work. Flies still gets in!
Every corner of the house got flies!
Kitchen flies
Toilet flies
Bedroom oso flies!
All utensils must be covered!!!

Maybe in another 10 yrs all the berbillions trillion flies will be gone?