It will get painted. FRP is a very common structural material, been in use for decades. It’s more expensive and tough to work with, but a great solution for difficult scenarios, like when fitting around odd shapes or when weight is a major concern. We use FRP regularly for seismic bracing of existing structures, for example, wrap an old concrete column with FRP so it will better survive an earthquake. In this case, I imagine the appeal is the extreme light weight simplifying foundation work. Pay a lot more for FRP, pay a lot less for everything else. That’s usually how we end up installing FRP.