Cecil Moore wrote:

If waves are not 'doing things' to other waves, how
are reflected waves eliminated by thin-films on glass?

A reasonable question, for a third grader. It's like asking: if '-2'
is not doing something to '2', then how can the result be zero when
they combine? For the case A + B = 0, B does not change A, and A does
not change B even though their sum happens to be zero. (Certain other
problems arise when you try to algebraically add commodities which
cannot be negative - power for example.)

As I've told you many times, you could keep from becoming confused on
these points if you would work them through from the standpoint of
fields, rather than power. Not doing so is leading to problems in your
understanding of what actually goes on.

Imagine you're floating above the ground between two closely spaced
football field sized capacitor plates. There is one on either side of
you, and they are parallel to each other. Consider now that one of
them becomes highly charged with respect to the other, and to Earth.
(Some source of energy would be required in order for this to happen
and to keep it charged in air.) You would then experience a strong
electric field.

Now imagine the other plate becomes highly charged in magnitude and
polarity equal to the opposite plate. It now produces a field equal
in magnitude and opposite in direction to the other plate. The net
field from your perspective is now zero, but one can imagine that from
a different perspective the total field is much greater with the two
plates being charged. But you'll note that nothing actually happened
to the field from either the first plate or the second plate, yet
between the two plates their effect was canceled. Their ability to do
work on a charged particle is negated. But in the way that many of
your references points out, that ability has moved to different points
in space. Please note that nothing moved that 'ability' there other
than the charge which was applied to the second capacitor plate.

An interference pattern doesn't 'cause' energy to move around, fields
don't move other fields just as waves don't move other waves and
photons don't move other photons.

73, Jim AC6XG