Because modern headlamps are made of softer polycarbonate (PC),
trademarked as Lexan, a hard acrylic outer coating and UV protectant has to be
applied by the OEMs at the time of manufacture.
Although harder, the very thin acrylic (trademarked as Plexiglas)
surface layer will still scuff and wear from accumulation of scratches
from washing and road grime impact. This is hazing and, aside from deep debris
impacts, it's a surface effect and light is defracted through these scratches.
What sets the GlassyLite apart is the trade-secret Nano Sealant that provides a better, longer-lasting protective layer than wax. The Nano Sealant doesn't bond with the molecules in the PC lens, but has molecules small enough to latch onto and reside in the gaps so that it holds better than wax. The sealant is not designed to work on Plexiglas (acrylic), due to the difference in surface adhesion. It's also about as hard as the OEM acrylic coating.