Looking at TS 2nd photo, can guess roughly already why. The project was built right next to a what appears to be ex-mining pond/lake?

Maybe architect/engineers figured it wasn't wise to go below the lake water level. Since this a PPR (I think) maintenance coz in the long run, it is going to be costly, in terms of pumps and other infra maintenance. Tenants in PPR aren't known to be good paymasters of maintenance fees.

**added....  From Google Map, it seems the development area may have been partially reclaimed land. Don't think natural landscape can be so straight especially at lake edge. Even more reasons to not build underground/basement carparks.