Light is MORE than just two waves at 180 degrees.

Normal light can be described as "circularly polarised" in that it has equal amounts of energy in each direction (perpendicular to the "ray" path) Polarising lenses "resolve" this light into one direction and the amplitude of the "resolved light" is proportional to the sum of all the sines of the angles to the incident polarised components.

Once you've resolved it once, you can resolve it again and again, each time reducing the amplitude according to the sine of the angle between the incident polarised beam and the polarising filter.

if there were only two components, you wouldn't get this effect and you could extinguish all the light with any set-up of the third lens. But since you can't, then we know that light isn't this "simple".

(and anyway, Relativity requires that there is no a priori "special" direction (or 2 directions) for the light to vibrate in. We merely use convenient mental notions of "up and down" vs "left and right". You might equally well imagine two planes, EACH at 45 degrees to the vertical, and you can set-up your polarising lenses this way and get exactly the same effect.)