Silver is not optimally reflective even when first applied. These reflectors were supposed to be polished monthly. The preferred and most reflective material is an aluminized vapor coating. This is the neat stuff they use in microscopes and in mirrors for aiming lasers. Most of the higher quality lamps use this.
Some lights also use a bulb shield, like a cup in front of the bulb.
It blocks direct light from the bulb to the lens so that only light from the designed shape of the reflector passes through the lens. This reduces stray light above the cut-off. A word about bulbs Halogen bulbs have been around for about 30 years now. Most of the replaceable bulb type lamps utilize a halogen bulb. Three common types of single-filament halogen type bulbs are H1, H2 and H3.