Why do shooters often wear yellow glasses? And perhaps in the same vein: why is street lighting often yellow/orange?

Answer

You will have to ask them yourself why shooters often wear yellow glasses. I suspect it has something to do with fashion.

Why the street lighting is yellow has to do with efficiency. A material emits light when its electrons pick up enough energy to move to a higher energy state. This ‘picking up’ of energy can be done by absorbing a sufficiently energetic photon or by collisions with other atoms or electrons. If afterwards that electron (spontaneously) falls back to the original lower energy level, a photon is emitted with a frequency (color) that is determined by the energy difference between the initial and the final state.

http://www.mhhe.com/physsci/astronomy/applets/Bohr/frame.html

In the resistance of an incandescent lamp, the electrons can occupy very many energy states, which are also very close to each other. As a result, the electrons returning to their ground state can emit photons with many different energies (and therefore frequencies). A light bulb gives a continuous spectrum, which we perceive as white light.

The lamps used for street lighting are gas discharge lamps (analogous to fluorescent lamps or energy saving lamps). Inside that lamp is a gas (sometimes of a single substance). The atoms are excited by an electric current and the electrons move into a higher orbit. When falling back, they emit a photon, but because we are now all dealing with identical atoms, the same few energy levels always occur. A gas discharge tube will therefore only be able to emit one or a few frequencies (colours).

In sodium lamps, the energy levels of the electrons are such that light with a wavelength of about 600 nanometers is emitted. It is therefore impossible to perceive colors in such lighting. Sodium lamps appear to have a particularly high light output in relation to the electrical power they require. The fact that our eyes are also most sensitive to yellow light is a bonus and makes them suitable for street lighting.