Tell that to the folks in Guam. . . jus sayin
UV and ocean exposure with humidity is no joke there. I swear I've seen fiberglass ladders "rust" (degradation resulting in material flaking) away over a few years. . . those are touted as corrosion-proof 
So, fiberglass ladders in Guam are indicative of how plastic "asphalt" roads in Hawaii will fare?
How does that work?
I have a fiberglass ladder. If you leave them outside in the elements, you're going to get some discoloration and staining. Doesn't seem to affect performance or durability so far, and I don't see any flaking. I've owned this for over 8 years and stored it outside next to a shed.
I'm pretty sure you can avoid that by not leaving the ladder exposed to sun, dirt and rain -- like with most tools. Without knowing how they treat "plastic asphalt", I'm only guessing the engineers would have enough common sense to anticipate the effects of UV on the plastic.
I also have a vinyl fence. The documentation says if you buy white, it is more resistant to UV because adding pigment to the plastic interferes with that protection. They also say to not paint the fence, as that also can break down the UV protection. The fence is as sturdy after 15 years as it was new. It came with a lifetime warranty for the buyer, and a transferrable 50-year warranty if I sell the property.
So, while I'm not knowledgable on the exact composition of the plastic asphalt, I do know there are solutions to protect plastic from UV rays.
