visible light - How does interference move energy from destructive to constructive regions?

I recently read (sorry but I don’t have a reference) that interference is not only about destructive and constructive interference but moving energy from destructive to constructive regions according to conservation of energy. The place where this really bothers me is when light is being transmitted through glass. As light moves through the glass there is forward scattering of light where there is constructive interference between the primary and secondary waves; so light propagates forward. On the other hand, the light that back-scatters (or side scatters as well) destructively interferes with the primary waves (I am assuming that the light has already passed the surface atoms so reflection has already been accounted for). Said another way, I can set up a thin film such that the reflectance is zero (R = 0) and transmittance is one (T = 1), don’t I need energy in the waves to cause destructive interference to begin with? So how does interference account for this energy exchange?