Fiberglass vs. ABS For Caps

Why aren't there more American made ABS truck caps? Seems like it would be nice to have a choice. Just wondering.

Here is a comparison made by canopy manufacturer

Canopy Materials:
" Most canopies sold in the Australian market place have either
fibreglass or ABS plastic shells. Fibreglass has a higher load bearing
strength than ABS, but ABS has higher impact strength than fibreglass.
Since it is not recommended to put any load directly onto any canopy
(see below), the greater impact strength of ABS can provide a real
benefit in the event of accident damage. In many impact situations
where fibreglass will crack or shatter, the ABS will survive
unscathed, although minor damage to both materials can be repaired.
Generally, offroad users prefer ABS canopies because they withstand
the vibration and shock of rough roads whereas fibreglass can tend to
crack in similar circumstances. The external texture of canopies is
either "leathergrain" or "smooth", depending on manufacturer's
production moulds. "Leathergrain" is more forgiving when it comes to
showing minor scuffing - it doesn't show the marks as easily..."

http://www.blueys.com.au/acc_canopies.htm