Having the doors of a vehicle open while driving is **prohibited** for several safety reasons:

- **Passenger safety:** All passengers must be seated in their seats and not move during the journey. This ensures they are protected in case of sudden braking or an accident. Open doors could allow passengers to fall out of the vehicle, which is extremely dangerous.

- **Vehicle control:** The driver must have enough space and visibility to operate the vehicle safely. Open doors can obstruct the driver's view and make it difficult to control the vehicle, especially in strong wind conditions.

- **Traffic regulations:** Traffic regulations state that passengers should get in and out of the vehicle only when it is stopped and from the side closest to the curb. This implies that the doors must be closed while the vehicle is in motion to prevent accidents from opening unexpectedly.

In summary, keeping the doors closed is essential for the safety of all vehicle occupants and to comply with traffic regulations.