Black funk on driveway

Does anyone know what the black funk is on driveways? It power washes off fairly easily but keeps coming back.

Is it some kind of mildew or something? Is there a product that can be easily applied to slow down its reappearance?

No overhanging trees, gets a lot of sun so the concrete dries fast and stays dry. Cars not leaking and are parked “downstream” from worst areas.