optics - Understanding reflection through polarization

I came across the following explanation:

The source of this so-called reflected light is not simply that the incident beam is reflected; our deeper understanding of this phenomenon tells us that the incident beam drives an oscillation of the charges in the material, which in turn generates the reflected beam. From the figure, it is clear that only oscillations normal to the paper can radiate in the direction of reflection, and consequently the reflected beam will be polarized normal to the plane of incidence.

Now, my question is what determines the direction of reflection?

I know that the angle of incidence is equal to the angle of reflection. But given that it is the charges in the material that generate the reflected beam, why can't the direction of reflected beam be random? Why is its direction well defined? Should the above law of reflection be blindly accepted due to experimental evidence?