Just came back from the dealership. Turned out that the door itself was aligned well; it was the vertical black part of the driver door adjacent to the B-pillar of the rear door that was not fully pushed in. The mechanic was able to adjust it in 10 minutes. I've attached the pictures for your references.
Before
After
The mechanic told me he was glad he did not have to adjust the striker because doing so would often make the door harder to open/close...